BeatMix - Enables Shuffle and Radio for multiple artists in Spotify
PartyWith - Connecting people who love to party - anytime, anywhere.
Playlist Machinery - Tools that help you create & organize your Spotify playlists
Flock Trips - Bachelor parties planned, organized, and squared away
Slackbox - Spotify playlist collaboration through Slack
Party with a Local - Party with a Local is a free app that connects travelers with locals that want to party.