Free program Tunatic analyzes whatever audio is playing on your computer (whether through a microphone or your desktop) and gives you the artist and track title.
Ever thought what is this song? Let Tunatic hear it and you will get the artist's name and the song's title within seconds. Tunatic is the very first song search engine based on sound for your computer. All you need is a microphone and Internet access.
Tunatic works pretty well with more recognizable songs, but can't always catch lesser known songs. However, if you've got a Mac and you want to contribute to the Tunatic database, give Tunalyzer a go.
Tunalyzer (when installed and enabled) scans your computer for music. When it finds a song that is not in Tunatic's database yet, it analyzes it and sends its audio fingerprint and metadata (title, artist, etc.) to the Tunatic server. Thus, that song can later be identified by other Tunatic users.
Get it here ..