Partyhero - Pass your friends the aux!
Party On Demand - Have a party delivered to your door in 60 mins or less.
Slackbox - Spotify playlist collaboration through Slack
PartyWith - Connecting people who love to party - anytime, anywhere.
AuxParty - Listen to Spotify & SoundCloud with friends and coworkers
Party with a Local - Party with a Local is a free app that connects travelers with locals that want to party.