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
Bandcamp - Discover amazing music and directly support the artists who make it.
Maloja - Simple self-hosted music scrobble database to create personal listening statistics.
SoundCloud - Enjoy music & follow favourite artists
Last.fm Scrobbler - Scrobble music all around the web!
Pandora - Pandora Radio is a free (ad-supported) internet radio founded in 2000.