This social network is not as popular as MySpace, but it also hasn't been corrupted by marketers and fake friends. Once available to students only, Facebook has opened its doors everyone and has made dozens of third-party applications available for members to use on their pages, from iLike (music sharing) to Graffiti (lets you draw on your friends' profiles) to Flixster (movie reviews) to Wis.dm (poll your friends!).