Shazam
What's that song playing? Point your phone at the music and find out with Shazam iD.
Shazam iD for Symbian S60 3rd ed. works just like Sony Ericsson's TrackID. It uses the same database from gracenote.com. Start the program, point your phone microphone to some source of music, hit "Tag Now," and Shazam will record 10 seconds of the song, make a fingerprint of it, send it to its server, and tell you which song you're listening to. The fingerprint is just 2 kb, so identifying a song with Shazam hardly costs you any mobile data traffic.
Shazam is very tolerant to background noise. I managed to identify tracks that were playing in noisy bars and supermarkets.