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
Spotify - Map shows when two people play same song at same time
TuneIn Radio - With TuneIn Radio Mobile, your mobile device becomes the radio.
SoundCloud - Enjoy music & follow favourite artists
Jamendo - Jamendo app is a free Android music player that allows you to download and listen to music legally for free on your mobile device.
Pandora - Pandora Radio is a free (ad-supported) internet radio founded in 2000.