I have use adsense in mine for months without any issues and I usually earn around $5k plus per month just from having them in Facebook applications.
Yeah, I think there would be more profitable ones for FB other then using Adsense. I can't think of any in particular at the moment, but just look around and I'm sure you'll find who the "industry Best" are for your purpose of integration with your FB Apps. Good Luck!
maxmed, You could simply just run the ads yourself using: http://www.openx.org/en/ad-server/facebook-app-get-started What niche is your App? You could then just run some CPA Ads, as well as maybe advertise appropriate Clickbank Products, etc. Hope this Helps!
This is the first time I've ever heard about running Google adsense ad on facebook. How did you do that? And how can we manage the account?
Iframe the adsense code. We used rockyouads and cubics which are the big 2 ad networks that specialize facebook advertisements but we found they paid very poorly like 0.01- 0.05 a click, where as using adsense we have been averaging about $0.40-$0.50 a click. Link units do best if you know how to place them properly.