I think this is pretty sweet. The idea is simple, and it's well executed. As a host all you need to do is to connect the app with your Google Play Music account (other services, like Spotify is on the way). Then both you and your guests can add songs to the playlist. If enough guests downvotes a song it will be skipped. As a host you have veto power. Oh, and an iOS version of the app is in the works!
Teleport
QCast Music