Would it be too cheesy or abusive to have showdowns? Puppyshowdown.com came up yesterday or the day before and had a good interface. What if you had musicians pick one or two of their songs to be used in head to head, this or that, contests. You could have a showdown each month then release a compilation album using the winning tracks. Revenue from the album would be shared with the musicians, you could get a small cut, and it would be a cool way for people to discover new music that has been filtered by their peers. This won't make a ton of money but it could be one little piece of the puzzle down the road.
There was a piece on NPR a few weeks ago about a classical music company that is doing very well releasing targeted albums on iTunes. They find out what people are searching for then compile their albums and choose relevant keyworded album titles. You could use your giant musician base to pump out indie albums to iTunes and other digital music catalogs. The albums could also be crowdsorted. You research and pick an album topic and title then set up a contest, the users crowdsort relevant tracks, you compile and release the digital album.
I don't know how you want to interact with other platforms but you could push updates to FB and the like "I just voted for X to be included on the upcoming album Y via Fandalism"
You could also make an app out of this functionality and people could listen to tracks and vote head to head or even just thumbs up or thumbs down pandora style. Everyone who was listening and voting would be sorting music for you.
I like to find new music but it takes a ton of effort to sort through totally unknown artists. Make it social and fun and empower sorters to contribute to a project (the albums).
"Help build the next great indie album @Fandalism"
Sorry for rambling but you just went from a music sharing site to an independent music label in 5 minutes.