22tracks - DJ curated Spotify playlists on iOS
Until AM - DJ in your browser with this SoundCloud music mixer
BandNext - Discover bands that sound similar to artists you already love with BandNext. A single click saves your results to a Youtube playlist.
Songlio - Free musical guessing game: race friends to name that tune
Spotify - Map shows when two people play same song at same time
Fretello Stage - Jam, record and share your music in the blink of an eye