Spotalike - Spotify playlist with similar songs, according to Last.fm
Lazyset - A Spotify playlist mixing Facebook Messenger bot
MusaicFM - An iTunes like screen saver based on Spotify and Last.fm
Slackbox - Spotify playlist collaboration through Slack
Bowtie - Bowtie is a desktop accessory that allows you to see and control your music (iTunes, Spotify...
Party Blends - A way to blend your friends favourite tracks into one Spotify playlist.