Turntable.fm is a social music site that allows users to tune into a station and listen to peer-selected music or become a DJ themselves. The service is young, but it has grown virally over the past few weeks. DJs are voted as “lame” and “awesome” based on song preference, so it’s easy to tell who has good taste. Now, users can participate and listen on the go using the free iPhone app. At the moment, you have to have know someone on Facebook who already has an account in order to sign up, so it may be tricky to get invited until the site goes public. For those lucky enough to have an account, check out the mobile app and let up know how it works.