About a year ago, at a party with a couple dozen Open Source and "community" people, I suggested to someone from Google that a music search where you could simply hum a few bars of a tune to find the song would be a very cool new feature. We chatted for about 10 minutes about the complexity of the problem -- which went way above my head.
Today, I read that someone's done it. Have you tried Nayio yet? I can't get it to work with Firefox (or maybe it's Firefox on Mac, not sure.) If you do get a chance to try it out, please let me kno if it works for you.
update: Ahh. It requires an ActiveX control. Well, I went over to Parallels and fired up IE, installed the ActiveX control, recorded myself humming a few bars of the theme from Sesame Street, pressed the Search button and IE crashed.