Myspace founders Chris DeWolfe and Tom Anderson have had an uneasy relationship with the music industry. Nearly every music act has a MySpace page; some of them, like British pop diva Lily Allen and American psychedelic-funk purveyor Gnarls Barkley, have used the social network to become stars. But two years ago Universal Music Group discovered unauthorized songs from U2 and Jay-Z on MySpace and sued the site in federal court. MySpace Music, scheduled to launch in September, promises to be the most significant rollout of a digital-music service since Apple's (AAPL, Fortune 500) iTunes. It will enable MySpace users to listen to any song from the catalogs of the three music giants free. There will be on-screen ads along with that music, but yes, it will be free. And that includes U2 and Jay-Z-and Christina Aguilera, Kid Rock, and rap superstar T.I. DeWolfe says the key to the new service is this: Users will be able to visit the pages of major label artists and click on the songs they like as they listen. Then they'll be able to create playlists on their own pages made up of those tracks: "There will be a button that says, FOR THE FULL CATALOG, CLICK HERE," he says. "That's what's never been done before." The idea is that people will use the playlists to personalize their MySpace page, which, in turn, boosts traffic. "Think about why people go to a music service," he says. "They go to iTunes because they just want to get the songs and get out. MySpace is different. It's like going to your friend's house, and they have cool music playing in the background that makes the experience that much better."