FIEND.fm - "Hot or Not" for music discovery: 2 hrs of tracks in 2 mins
Bandcamp - Discover amazing music and directly support the artists who make it.
Pacemaker - Create and share mixtapes with friends
SoundCloud - Enjoy music & follow favourite artists
Boil the Frog - Create a seamless playlist between any two artists
Pandora - Pandora Radio is a free (ad-supported) internet radio founded in 2000.