Until AM - DJ in your browser with this SoundCloud music mixer
Playlist Machinery - Tools that help you create & organize your Spotify playlists
Songlio - Free musical guessing game: race friends to name that tune
Heartbeat - Listen to music with your friends together, on Spotify
Playlistify - Make Spotify playlists from 1001tracklists & setlist.fm sets
Partyhero - Pass your friends the aux!