Cost: Free with commercials; $5 a month for commercial-free listening; $10 a month for offline and mobile access.
How it Works: Form personalized playlists using songs you already own and those from the library of 16 million songs. Or make custom radio stations featuring artists of your choice.
Cool Perks: Free applications that help you find new music and enhance your experience. (Songkick pinpoints local concerts; TuneWiki displays lyrics.)
Drawbacks: It can be a little tricky to hide what you’re listening to from your friends’ Facebook news feeds. Limited classical-music selection; no Beatles.
Best for: Serious Facebook devotees. It seamlessly blends social networking with music listening.