Social media is all over the place. But all are financed via advertisement and thus the focus of the developers of the platform is set on making the experience for advertisers the best possible (and generating a profit). App.net has the ambiguous goal of revolutionizing the social-network market with a user financed network. They are currently in an Kickstarter like process of funding (goal set to $500,000 and ca. $200k missing and 4 days left as of writing).
I backed the project even though I think this goal is hard to hit. The mentality of 'everything free' is not going to be taken away. Even though I would like to see this project rise. If it works, it will be probably be awesome.