AudioTag - AudioTag.info — is a free music-recognition service.
Spotify - Map shows when two people play same song at same time
Shazam - Shazam is a mobile app that recognizes music and TV around you.
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
ACRCloud - Automatic Content Recognition (ACR) cloud services for Audio Recognition ( identify music, ads ), Broadcast Monitoring, Second Screen, Copyright Protection.
SoundCloud - Enjoy music & follow favourite artists