The Wub Machine - Turn any music into Dubstep, Drum & Bass, and more.
Parallel - Listen to music with friends over Spotify at the same time
The Eternal Jukebox - For when your favorite song just isn't long enough
Slackbox - Spotify playlist collaboration through Slack
YOU.DJ - Mix SoundCloud music and Youtube videos live in your browser.
Join My Playlist - Listen to music live together with your friends in Spotify.