The past two days, we’ve seen a wide variety of companies presenting at TechCrunch50 somehow make use of Facebook — some built apps or used Pages, some accessed profile data, the news stream or photos through Connect. Here’s a quick review of what we saw, in chronological order, including links to other sites that have covered the companies in more detail.

SealTale: This doesn’t seem like a new idea. SealTale lets you place an endorsement widget on a web page, including a simple frame on Facebook. More on CNET.

Udorse: An endorsement site where people can endorse items in their Facebook photos, potentially convincing friends to buy them as well. More on TechCrunch.

Refmob: Cross-site service where people can get paid for referring their friends to jobs; includes a way to refer Facebook friends. More on VentureBeat.

Mota Motors: Used car marketplace site that accesses Connect to let buyers and sellers include their real Facebook profile photos. More on SocalTech.

YourVersion: News discovery engine site that lets you share stories on Facebook. More on TechCrunch.

Metricly: Simple analytics service that includes a way to track fans on Facebook. More on VentureBeat.

Crowdflower: Online workforce placement service that apparently includes a Facebook app where you can earn virtual currencies in exchange (I don’t see the app). More on Caem.la.

Cododot: Event-planning and invitation service focused on women. It lets you post invitations to Facebook. More on Techgeist.

Threadsy: Social stream aggregator site that lets you read information from Facebook along with other social sites. More on CNET.

Radiusly: Imagined as a sort of Twitter-LinkedIn hybrid, the company also lets you post items to Facebook. More on VentureBeat.

[Photo via Noah Hendrix.]