Playlistful - Collaborative playlists for parties!
Pyro - Spotify music voting for parties
Festify - Festify is a free Spotify-powered app that lets your guests choose which music should be played...
Party On Demand - Have a party delivered to your door in 60 mins or less.
klaep - music collaboration - klaep is a social music collaboration network for musicians
Party Play - Introducing Party Play. One playlist for multiple users.