Social Media/Social Network Ad Networks List
So you can run ads on these networks and they'll show on Facebook apps, Myspace apps, Bebo, Friendster, etc... whatever you choose. Most of them are targetable by user demographics as well. I've had great success with some of these networks in the past, primarily with what I consider 'stupid' CPA offers, like mobile IQ/Crush offers, or quizzes... Anyway, have a look and see if any of them work for you
Check it out here:
A complete list of Facebook ad networks