Knowthelist - Knowthelist - the awesome party music player Easy to use for all party guests
Spotify - Map shows when two people play same song at same time
Song Director - Song Director is a program that plays and keeps track of all your music files.
SoundCloud - Enjoy music & follow favourite artists
ServeStream - ServeStream is an open-source application that is intended for HTTP media player streaming, and the media server browser comes with the alluring support for custom online radio and Shoutcast streams.
Last.fm - The world's largest online music service. Listen online, find out more about your favourite artists, and get music recommendations, only at Last.fm