You’re no doubt familiar by now with Zynga’s newest game, Treasure Isle. The scavenger-hunt game was released a little over two weeks ago, and immediately took off. Its gain of almost seven million new monthly active users easily places it on top of this week’s list of fastest-gaining Facebook apps by MAU.

The past week suggests a bright future for Treasure Isle. The rapid growth of its userbase means that the game isn’t yet ready to hit a plateau, like the first big success of the year, Playdom’s Social City. And at number 13 now and still moving, Treasure Isle will soon be among Facebook’s top 10 games overall.

Of course, Zynga is still supporting Treasure Isle with a significant marketing effort, which it could reduce at any time. We’ll look at Isle, Hotel City and the other games in more depth over at Inside Social Games. Here’s the AppData top 20 list.

	Name	MAU	Gain	Gain, %
1.	Treasure Isle	14,409,959	+6,862,487	+90.92
2.	Hotel City	8,663,088	+3,990,894	+85.42
3.	Static FBML	55,549,127	+1,095,314	+2.01
4.	LivingSocial	1,933,555	+977,654	+102.28
5.	Family Feud	1,929,908	+968,616	+100.76
6.	Facebook for iPhone	32,431,112	+865,325	+2.74
7.	Zoo Paradise	3,852,816	+711,269	+22.64
8.	Mall World	881,206	+676,705	+330.91
9.	Tiki Resort	5,221,827	+523,154	+11.13
10.	Bubble Island	5,724,107	+511,541	+9.81
11.	Your Luck [daily]	3,958,837	+482,655	+13.88
12.	Friends Emotions [Emociones de Amigos]	3,263,998	+452,623	+16.10
13.	iKarma	730,733	+422,967	+137.43
14.	Fish Friends	727,350	+407,082	+127.11
15.	Facebook for BlackBerry® smartphones	16,321,784	+353,827	+2.22
16.	Family Tree	5,082,283	+253,331	+5.25
17.	Kingdoms of Camelot	1,725,862	+207,800	+13.69
18.	Lover Of The Day	1,492,745	+200,053	+15.48
19.	Akinator	662,943	+197,658	+42.48
20.	¡Teclas Machucadas!	193,927	+179,445	+1,239.09

LivingSocial was losing users until recently, but it just began enjoying a large upswing in traffic, for no readily apparent reason. That could mean it has been doing more advertising, a possibility that’s supported by the company’s March raise of $25 million in venture capital. Now that semi-competitor Groupon, a collective buying site, is reportedly being valued at $1 billion, it’s probably reasonable to expect LivingSocial to keep pouring money into expansion.

Facebook for iPhone, which often shows up on these MAU lists, is once again enjoying higher-than usual growth. As we guessed last week, that growth is probably attributable to the massive press attention that Apple received from the iPad’s launch, and a concurrent lift in iPhone sales. Analysts are also predicting a strong quarter for Apple, with high sales numbers for the iPhone.

Your Luck [daily], an app from Appschain in the horoscope category, is getting rather large. Right below it, you can find iKarma, a significantly smaller app by a newer, eponymous developer. But note that iKarma’s new MAU growth is almost equal to Your Luck’s, and is still increasing, so it could someday catch up.