Bandcamp - Discover amazing music and directly support the artists who make it.
SoundCloud - Enjoy music & follow favourite artists
yungcloud - "the world's leading underground music streaming service."
Pandora - Pandora Radio is a free (ad-supported) internet radio founded in 2000.
Artrezor.com - New beta social network for sound lovers, including waveform player and uploads. And it's free.
Spotify - Map shows when two people play same song at same time