You use Spotify, your brother is an Rdio guy and your girlfriend is all about Beats. So sharing playlists is basically a no-go. Bop.fm's goal is to break down those walls by aggregating freely available music from a variety of sources. At the moment that list includes Spotify, Rdio, Beats, YouTube and SoundCloud, though you can only import playlists from the first two. When you sign up for Bop it detects what other services you're connected to, and automatically plays back a track from wherever it's available -- even if that's only as a video as YouTube. Of course, no music service is complete without its share of celebrity endorsers, so Bop.fm has enlisted Snoop Dogg, Lil Wayne and Paul McCartney to share playlists.