Want unlimited free music on mobile? Check out Playground.fm which launches today to deliver playlists created by members of its community. The secret sauce is that the songs have already been paid for by individual users, meaning Playground does not need to pay additional licensing fees to artists. The hybrid of Turntable.fm, Spotify, and Pandora’s models currently does not serve ads and hasn’t revealed its monetization strategy. [Source VentureBeat]