Knowthelist - Knowthelist - the awesome party music player Easy to use for all party guests
Jukebox - Collaborative music player
Song Director - Song Director is a program that plays and keeps track of all your music files.
Clicker for YouTube - The best standalone YouTube TV player for Mac
MixTape - Home of MixTape, an OSX application for creating beat matched mixes with simple export to the web or iTunes.
Spotify - Map shows when two people play same song at same time