There are several tools out there that will identify your music, such as MusicBrainz Tagger, but Tunatic is a bit different. Its sole purpose is to identify music you play it through your computer's microphone. So, if you're listening to the radio and hear a song and want to know what it is, you can hold your microphone up to the speaker and in a few seconds Tunatic will, or so its makers claim, identify the song. It's supposed to work for music of any genre except classical and be able to identify different versions and mixes of the same song. I don't know when the last time I listened to the radio while at the computer was, but I suppose this could be useful for some people. Tunatic is available for both Mac and Windows.