Spotalike - Spotify playlist with similar songs, according to Last.fm
Jukebox - Collaborative music player
MusaicFM - An iTunes like screen saver based on Spotify and Last.fm
Festify - Festify is a free Spotify-powered app that lets your guests choose which music should be played...
Bowtie - Bowtie is a desktop accessory that allows you to see and control your music (iTunes, Spotify...
PartyOn - Let everyone DJ together, anywhere