Tunatic is a free application for Windows and Mac OSX that can recognize & identify the artist name and title of a recorded song or music album through the microphone of your computer.
After the application is installed, make sure the source of the sound is near the microphone and click the Tunatic program to identify the song. The software then connects to an online server, tries to match the signature of the song against its own database and return the artist name and title, if found. Tunatic’s database contains signatures submitted by their community of users through a program called Tunalyzer.

This application is similiar to the TrackID/MusicID services available for Nokia S60 and Windows Mobile devices.

If you get an error about the server not being reachable, make sure ports 5747 and 5748 are open on your firewall.

Download Tunatic for Windows here and for Mac OSX here