PartyWith - Connecting people who love to party - anytime, anywhere.
Magic Playlist - Get the playlist of your dreams based on a song
Party On Demand - Have a party delivered to your door in 60 mins or less.
Spotalike - Spotify playlist with similar songs, according to Last.fm
Party Play - Introducing Party Play. One playlist for multiple users.
Playlist Machinery - Tools that help you create & organize your Spotify playlists