Spotify - Map shows when two people play same song at same time
Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.
SoundCloud - Enjoy music & follow favourite artists
Bigtent - BigTent is a web-based organization and communication portal for groups.
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
Nabble - Nabble is a forum software that are embeddable and fully customizable with scripting language.