Slackbox - Spotify playlist collaboration through Slack
Bowtie - Bowtie is a desktop accessory that allows you to see and control your music (iTunes, Spotify...
Partyhero - Pass your friends the aux!
Muzzy - it’s a tiny and gorgeous iTunes companion that lives on your menu bar. For Mac OSX, its free!
Songmash - Create playlists with music that you and your friends love
Owlead - Grow your Twitter with valuable followers, effortless