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inTune.fm is a new application for Facebook that allows you to discover music that people in your network, and friends, have uploaded. While it is similar to anywhere.fm in appearance, function, and interface, inTune.fm works only inside of Facebook.
So far there are over 80,000 songs available, so there is plenty of free music for you to check out, and you can share anything you uploaded also. While listening, you can also see which of your friends enjoy the same artist, then mouse over their info to quickly check out who else they like so you can explore more new music.
Course, with the rumor that Facebook may be adding a new MP3 store, one has to wonder how long they will allow free music.