[bmelton]

This is almost exactly the technology behind Shazam, which has a fairly extensive catalog. Shazam 'listens' to a song when you hit a button and captures microphone data from your phone. It then takes that recorded data and listens for 'key points', which it hashes and uses to compare against its catalog.

If you want to know more about how to implement it on your own, you could use this as a resource: http://www.redcode.nl/blog/2010/06/creating-shazam-in-java/

I assume the biggest drawback to be that Shazam uses a microphone, which is obviously subject to ambient noise. Shazam doesn't actually seem to have much of a problem with this, but I'm guessing a passive listener that sampled the audio output device instead of a noisy ambient microphone would work much more reliably.