By now, most people have come across a celebrity’s page on Facebook. More and more musicians and athletes are taking to Facebook Pages to engage with fans through personal updates and photos, which fans see in their home page streams.

In fact, according to PageData, there are 230 musicians & bands and 41 athletes on Facebook with over 50,000 fans. But which celebrities are eliciting the most responses and reactions from Facebook fans?

According to Facebook, Vin Diesel and Susan Boyle are far and away the most engaging celebs (as measured by the total number of fan comments, likes, and wall posts), with over 700,000 and 400,000 responses during April, followed by Britney Spears and Ashton Kutcher – with over 200,000 responses each.

How? As we profiled last month, Vin Diesel (who now has nearly 4 million fans on Facebook, putting him third to only Barack Obama and Dr. House) has grown his Facebook audience dramatically by posting authentic status updates and photos during recent weeks. Fans have always loved this kind of information from celebrities they follow, and Facebook provides a powerful way for them to share easily.

Here are the 15 most engaging celebrities on Facebook, as measured by the number of fan comments, likes, and wall posts for April 2009:

1. Vin Diesel – 737,000
2. Susan Boyle – 412,000
3. Britney Spears – 212,000
4. Ashton Kutcher – 202,000
5. Lady Gaga – 198,000
6. Ashley Tisdale – 87,000
7. Green Day – 179,000
8. Barack Obama 156,000
9. Depeche Mode – 142,000
10. Jonas Brothers – 133,000
11. Linkin Park – 127,000
12. Coldplay – 113,000
13. Bon Jovi – 103,000
14. AC/DC – 102,000
15. Roger Federer – 101,000

Two weeks ago, we noticed that Facebook had begun testing its virtual currency gifting program with branded virtual gifs. In the test, users were able to give friends special virtual gifts – in this case, Mars candy bars like Snickers and Milky Ways – that were also bundled with 10 Facebook credits. Those “credits” are Facebook’s virtual currency, which can then be redeemed in the Facebook Gift Shop.

Today, Facebook expanded its testing of credits bundled with branded virtual gifts to the home page with a campaign for the new movie Terminator Salvation. This is the first time credit gifting has been displayed this prominently that we’re aware of, and if the history of the Facebook Platform is any indication, it’s likely to boost virtual gift send rates significantly. That means more reach for advertisers through Facebook’s virtual gift engagement ad unit – and more revenues for Facebook.

However, Facebook will also have to be careful not to “overincentivize” virtual gifts. Since the Facebook Platform launched, developers have incentivized users to take “viral” actions by rewarding the senders of those viral messages with points or currency in those applications. (This led to a lot of user complaints about application spam, and Facebook has since instituted Platform policies prohibiting app developers from incentivizing the use of Facebook communication channels.) However, Facebook hasn’t gone that far in this case – here, the receivers are the ones getting the bonus currency, not the senders.

Facebook is clearly moving aggressively to test expansions to its virtual currency. Last week, Facebook confirmed to Inside Facebook that it is planning on launching tests integrating its virtual currency into Facebook Platform applications soon. Under such a system, Facebook users would buy currency from Facebook and spend it in applications, whose developers would then get reimbursed by Facebook (less a “transaction fee,” of course) for their work.

In other words, Facebook’s virtual currency is increasingly becoming the basis of transactions inside the Facebook ecosystem.

Another phishing site is making the rounds on Facebook today, and this time it’s “areps.at” (not linked). However, like other phishing attacks on Facebook, Facebook started blocking all links to the site once its security systems detected its spread this morning.

Facebook doesn’t reveal how many people scams like these affect, but has said in the past that similar phishing attacks have reached “less than 1%” of users. 1% of 200 million is still a significant number of accounts, but it’s likely that Facebook discovered the site earlier than that.

These kinds of phishing attacks are popping up with regular frequency now, and Facebook’s security team continues to develop early detection systems to fight them off. However, attacks like these do illustrate one type of social networking security challenge that’s likely to persist – click through rates on messages from friends are always going to be high, even if the contents of the message are somewhat out of the ordinary.

Facebook’s security team has been working with Microsoft in recent months to detect and fight off variants of the Koobface worm. For more information, check out our previous coverage:

• Why Facebook Is Working with Microsoft to Fight Koobface Virus
• Update: Facebook Security Fighting Koobface Worm, Chain Letters

Facebook has increased the size limit on photo albums from 60 to 200, thanks to a new storage system dubbed Haystack. The jump in storage capacity was a necessity for many users, as Facebook is the largest photo-sharing site on the Web.

More than 15 billion photos have been uploaded to Facebook, with an average of  220 million new pictures showing up each week. Facebook creates 4 images for every one added, and those huge numbers required a more robust support system. The new infrastructure reduces bottlenecking brought on by the enormous amount of metadata information needed. This translates into quicker access to photos by users.

Facebook said sharing has increased since the limits were gradually increased over recent months. The additional space could also draw in more users who may have been reluctant to make the move to Facebook from other sites based on Facebook’s limited album numbers. These users generally send in a lot of secondary traffic as they promote their own photos and steer friends and relatives to their online albums.

Facebook is obviously recognizing and catering to how the site is being used, and this move should enable Facebook to keep more and more traffic from the traditional photo-hosting sites.

As we continue our look at the Facebook Platform payments ecosystem, today we turn our attention to AdParlor, a full service social network ad agency that operates its own virtual currency monetization platform and social ad network. We recently spoke with AdParlor CEO Hussein Fazal about his view of the payments landscape on the Facebook Platform and AdParlor’s approach to the market.

Inside Facebook: Why did AdParlor make the transition from traditional online advertising to offers and direct payments for virtual currency?

Hussein Fazal: Feedback from application developers told us that banner advertising was making up only 5 to 20 percent of overall revenue, whereas the rest was coming from offer walls and direct payments. Virtual currency is doing so well, but keep in mind that not all applications are suited for it. There are applications out there that do in fact make a majority of their revenues from banner advertising.

We started in the ad network space and are still focused on growth within this space; however, we have also brought on dedicated individuals to grow our virtual currency and wall offer piece. When it comes to revenue potential, the offer wall outperforms the ad network. Right now the ad network piece is a larger portion of the business because we’ve been doing it for over a year, but virtual currency will take over at some point. Given the fact that we started in the ad network space, we had relationships with all the major app developers.

How would you compare your business across different platforms and countries?

AdParlor primarily focuses on Facebook and MySpace – that’s where most of the transactions are. In terms of banner advertising, we’re on most of the social networks, but the focus is on Facebook and MySpace for virtual currency monetization.

There’s not much disposable income in some countries where social networks are strong. In Malaysia and the Philippines, it’s difficult to monetize because there’s not much willingness to spend. The Chinese market and some of the other Asian markets are a bit different because they have massive populations that have enough disposable income, and are comfortable playing games with built-in virtual currency such as RPG’s. It’s difficult for us to get into the Asian market because of the language barrier and the difficulty of building relationships with strategic players in those local markets.

Who are the key players in your value chain and what value does AdParlor deliver to each?

On the application developer side, the value for app developers is that they don’t need to worry about going to hundreds of different offer providers, managing payouts, seeing what works and what doesn’t, and handling user complaints. By going through AdParlor, given our volume, we can negotiate better rates when it comes to completing offers. Developers can focus on building applications. We help monetize.

In the same way, the offer provider has no interest in going to each app developer and would rather go to aggregators like us that can draw users from different types of applications. We work with around 30 offer providers, 10 of which we work closely with. They provide us with best offers at highest payouts.

In addition, we partner with payment platforms, including Zong and Social Gold. We’re also looking at something pretty interesting right now, which is bringing landline companies into the value chain. Users can buy virtual currency by billing to their landline bills.

Can you walk us through the transaction process, from the end user to the advertiser?

Users see an offer in an application asking them to complete a survey in return for, say 10 credits. They click on the survey and complete it through AdParlor. The survey provider then pays AdParlor a certain amount, say $5 dollars per survey. We pass on a portion of that to the application developer, ranging from 70 to 90 percent, sometimes higher if the developer is pushing a high amount of volume. Based on the amount we pass on, that’s how many credits get passed on to the user.

From the user’s perspective, what’s the psychology of purchasing virtual currency?

You would be surprised how many people are willing to fill out surveys in exchange for virtual currency. Let’s say a user is playing Bingo on Facebook on a Monday afternoon. See it as entertainment. Just as people pay money to play video games, when they run out of credits, they’ll pay for more to continue playing. It’s like a cost of entertainment.

Are offers really aligned with users’ interests?

All the offers aren’t useless – they add value. For example, an offer may require you to signup for a DVD club for $1 dollar. In return, you get seven DVDs. For someone who is interested in movie services anyway and is looking to get credits to play Bingo, it’s a win-win situation. Every offer is different.

I imagine payment fraud is a problem you have to deal with?

It does happen that users put in stolen credit cards and fake addresses and phone numbers. In this case, a chargeback occurs. When offer providers finds out, they’re not going to pay. We go back to the application developer and reverse the transaction. If developers are thorough enough, they’ll make additional callbacks and take the credits back from users; however, if they’ve already sent it, there’s not much more you can do. That said, the level of scamming isn’t high.

Fraud gets caught at the top of chain: the offer provider may see that 10,000 surveys were completed in one second. We also have checks in place along the way: if the IP address points to a location that doesn’t match the postal code, that also raises a red flag.

So, it’s confirmed that Facebook is launching its own virtual currency test for applications. Thoughts?

Obviously Facebook is in an advantageous position. But at the end of the day, Facebook is another competitor – a big competitor, but that doesn’t mean other virtual currency or offer payment platforms won’t exist. We’re not anxious or excited, but it’s something to keep eye on. It’s going to be interesting to see how Facebook’s virtual currency test rolls out, and if the company decides to go with a full-fledged offer wall, what kind of offers it would have. With all the volume of user information it has, Facebook could do some really interesting stuff. For example, if someone wrote a Wall post about a Britney Spears concert they want to attend, Facebook might be able to use that info within an application to offer you a 10 percent discount to the upcoming Britney Spears concert.

In this economy, how are advertisers changing how they do online advertising?

That’s interesting. Before the recession, large brands were okay spending money on branded banner advertisements. Now they’re hesitant and looking for guaranteed results. From the ad network side, brands are shifting from CPM to CPA models: they don’t care how many times an ad is seen; they want to pay only if users sign up, so a lot of money is shifting from branding to actual action.

How’s your company doing from a financial perspective?

We’re profitable and doing quite well.

Where will the payment space go from here?

The key is to make all payment options available to users, whether it’s via credit card, mobile phone, or landlines. I don’t know if there will be much innovation in terms of payment, but Spare Change has an interesting model: users buy Spare Change credit and exchange this credit with whatever virtual currency there is within an application. The benefit of this is that if users play with five to 10 gaming applications, they can buy 1000 Spare Change credits and use them across apps.

Thanks for your time, Hussein. Any final comments you’d like to make to our readers?

The fact that we come from both the ad network and virtual currency sides means that we have a lot of relationships in place with advertisers and offer providers. AdParlor brings interesting and exclusive offers to the table. If an application developer wants to integrate with an offer wall, our self service system will get them set up in half an hour.

Sprout, a startup that provides brands with tools for creating apps and widgets for social networks, has announced a new Facebook package for companies wanting quick turn-around on a one-stop solution to Facebook marketing. The “F3″ service includes a Facebook application, Connect integration, and a Facebook Fan Page, which Sprout says it will turn around all in 2 weeks for $50k. Pitching all of these services in one easy package is a great way for any company new to the social media scene to jump in with both feet.

“With this bundle, we are offering the most aggressive pricing model available for building a robust social media program for Facebook,” said Carnet Williams, Co-founder and CEO of Sprout. “The Sprout F3 bundle offers a tremendous value for companies that are ready to take the leap into social media and want to engage fans with a fun experience while enabling them to share personalized brand messages with their friends.”

Companies will have access to tracking information, full interaction between the client site and Facebook through Facebook Connect, and a Fan Page promoting the company and application. This package also includes Sprout’s help to build the campaign, whether it be with existing assets and content or something fresh, as well as access to its Engagement Console to analyze and track the campaigns progress, see what’s working, and make adjustments as needed.

With Facebook’s launch of the new Fan Page, more and more organizations and individuals are taking advantage of the easy access to a customer base that Facebook offers. Larger companies are starting to see real results from their pages as the product continues to grow in popularity.

As we continue our look at the Facebook Platform payments ecosystem, today we turn our attention to virtual economy payment and analytics platform Twofish. In fact, just this morning Twofish announced the launch of a new product called Twofish EasyElements, an easy to integrate toolkit for managing virtual currencies in social networks and online games.

We spoke with Twofish President Lisa Rutherford about the opportunities she sees and the approach Twofish is bringing to market.

Inside Facebook: When did you see the potential in the virtual goods economy?

Lisa Rutherford: I was skeptical. I had been in venture capital and saw the rise of virtual goods in Asia. Many people said it would translate to the US. That model took off in Asia because Asia needed a new business model. The free to play model works in Asia because Asia needed to find a viable way to address piracy problems. The problem is that the US has business models that are working, for example subscriptions. I had a similar reaction to consumers’, which was: free to play is just another way to extract money from users. Then I realized that if you decouple the economy from monetization, a virtual economy can be a game play feature that enhances the game play experience.

Interesting. How does Twofish decouple the economy from monetization?

Twofish runs a virtual economy for you. We’re a virtual economy data platform. We capture enormous data that no one else does on currency, users, inventory management, etc. in an analytics framework. Using robust, simple tools, you can analyze price, items, macroeconomic flow, what types of users are buying certain items, and other variables enabling you to optimize revenue and the user experience. We’ve never had bad press from the consumer side of things. We didn’t say we could take money out of everything. Our goal is to enable more meaningful types of interactions.

What products do Twofish offer? (Note: This morning, Twofish announced the launch of  a new product called EasyElements.)

One component of Twofish’s core platform is a banking layer, which records the full credit and debit history for every single transaction that happens in a game. We keep history on individuals, as well as items. If you buy a gun in an elements-backed game, the gun has its own item account, which details who owned it, what they payed for it, etc.

The Twofish Elements Analytics tool gives you unparalleled access to currency, user, and catalogue data with the flexibility of dating mining and visualization. This robust tool captures data relevant to currency, sales, and user reports, macro flows, market activity, payment types, unit sales, revenue, etc.

Elements Analytics:

Now we’re launching Twofish EasyElements for casual social games that have a need for more lightweight tools. It’s easy to set up EasyElements in a couple hours. The first starter kit is CurrencyStarter. Like Jambool, it helps you get money into the system and your currency set up, but it’s different because you can brand your own currency across platforms, have separate exchange rates in different countries, etc.

EasyElements users can access data in a custom Google Analytics integration:

The CurrencyStarter allows you to turn on, sell, and track virtual currencies:

What challenges might Facebook face in launching its own a virtual currency system?

It’s smart of Facebook to begin testing out its own virtual currency because it was leaving money on the table. The company is secure and well-run, and we’re very much looking forward to plugging in. The challenge is that Facebook has to give something (data) back to developers. And since Facebook opened its Platform to application developers before rolling out its virtual currency system, there may be some ill will. By contrast, Apple has been more strategic with its store in not yet involving third-party developers. When Apple introduces its platform, it will be all fanfare and glory.

What are a couple characteristics of compelling virtual goods?

Branded virtual goods that signify individual knowledge of the giftee are successful. Giving a woman a bottle of perfume doesn’t seem that thoughtful, but if you know she wears Chanel No. 5, that signals a stronger level of communication and intent. It’s a way of saying I was thinking about you in a very personal manner. Another trend is around care-taking and making items consumable. Making dog food disappear, a rose wither, or a litter box fill up with poop has the added effect of making people come back.

In this economy, most start-up companies are hurting. What have you noticed in your own company?

Personally, Twofish hasn’t felt the impact. The economy has accelerated a lot of people toward new business models. A lot of start-up companies need to get revenue fast because there’s no venture capital support or large advertising budgets, so bootstrapping is common.

Earlier you mentioned that the free to play model in Asia and the extent to which it could be applied in the US. In the next wave of innovation, what direction will virtual economies take at a global level?

The free to play model from Asia won’t be exported around the world, but similar concepts will be used. In the Middle East and South Africa, there are places that have large diaspora populations and don’t have solid sovereign economies. This is an opportunity to have an online economy transact value and to build a digital economy far beyond gaming and social networks. From a purely classics standpoint, gaming and social networking are on the cusps of extreme innovation.

We’ll see a true digital economy evolve beyond virtual goods and currencies, and beyond games and social networks – a digital economy that’s localized just by being digital. In 1994, globalization was here and now, and today the world is globalizing more and more. The Web enables globalization, monetization, free trade, and the spread of information and ideas – why shouldn’t economies too?

Along with the release of the updated application directory today, Facebook has also made public for the first time the list of applications which it has certified in its Application Verification Program. 120 applications now appear with a “green check” in the application directory and a badge on their about page.

In addition, Facebook shared in more detail the what the exact benefits of Verification actually are:

1. Badging in the Application Directory: Users will see a green “verified” check mark next to your application name wherever it is listed.
   
2. Priority ranking in the Application Directory: When appropriate, Verified Apps will appear before any applications that have not been verified yet.
3. Badging on your application profile: On this page, users will see the official “Facebook Verified App” graphic in the left column.
   
4. Allocation boosts: You will also receive a two-bucket boost in both notification and requests allocations. You can see your application’s allocation buckets on the Allocations tab on the Insights page. These allocations will continue to be subject to our algorithmic reputation system which looks at various metrics and user signals.
   
5. Ad credits and discounts: You will receive $100 in credit to advertize with Facebook and discounts to paid Facebook events.

The verification program, which was announced last July and launched in November, is designed to give more prominence to applications which meet Facebook’s standard for user experience and security. Anyone can apply, but there is a $375 fee per year.

Along with the “Great Apps” program, which currently includes just Causes and iLike, the verification program is another part of Facebook’s efforts to improve the trustworthiness and reputation of applications on the Facebook Platform.

As indicated last week, Facebook turned on new application about pages with the launch of the new application directory this morning. Now, the new about pages look and feel like public profile pages with just a couple extra elements to let visitors add the app and see how many users the app has. Here’s how it looks:

Now, app developers can now send status updates and post other content to their app profile page stream that will show up in fans’ home page streams. It’s a new and interesting way for developers to keep their users engaged by posting interesting content.

However, becoming a fan of an application is a separate action from authorizing it when users want to engage with the app. Some developers may not want to send users outside the application canvas page to the about page just to get them to become a fan of the application.

Nevertheless, it’s another small step toward Facebook’s long term vision of communication happening through the stream. Facebook is incentivizing becoming a fan of all pages, not just application pages, by providing such prominent real estate to updates in the stream.

Some applications will have the challenge of figuring out what to do with separate pages that they (or fans) had established for the app. Just yesterday, Inside Facebook detailed two applications with independent pages with over a million fans. We imagine Facebook might be willing to merge these fans into the app about page to consolidate administration at same point in the near future.

Since the Facebook Platform launched two years ago, the application directory hasn’t changed significantly. However, this morning, Facebook launched a new version of the application directory more focused on promoting “Verified” applications and those apps friends are using. Altogether, the new app directory focuses a lot more on quality over quantity. Here’s how it looks:

As you can see, the most prominent sections of the application directory are now “Featured by Facebook” and “Applications You May Like.” The “Featured by Facebook” section contains applications that have been hand-picked by the Facebook Platform team, which marks the first time Facebook has taken an editorial role in curating the directory.

The “Applications You May Like” section shows applications that have achieved Verified Application status (meaning they meet Facebook’s requirements for user experience and security) as well as other applications rated highly by users.

Below the “Applications You May Like” section is a new section called “Recent Activity From Friends,” which is essentially a filtered view of the home page stream just for applications. Facebook is using this section to promote whichever applications your friends have used or engaged with recently. Facebook has also reduced the number of application categories from 15 down to 7.

The application directory has become a relatively minor source of new application user traffic over the last couple of years. However, the new app directory is primarily intended to reward the highest quality apps, as opposed to shedding light on the ones that have the most users or growth like the previous version did. That will ruffle the feathers of some developers, but ultimately achieves Facebook’s goal of encouraging the development of applications which fit its user experience goals.