Playlist Machinery - Tools that help you create & organize your Spotify playlists
Until AM - DJ in your browser with this SoundCloud music mixer
TrackStack - Easy Spotify playlist sharing and collaboration
Songlio - Free musical guessing game: race friends to name that tune
BeatMix - Enables Shuffle and Radio for multiple artists in Spotify
Fretello Stage - Jam, record and share your music in the blink of an eye