This specialized search engine could have a number of interesting applications. The speech and sound recognition is better than many of them that are out there, put it isn't perfect. The technology is called Multimodal Adaptive Recognition System.
You can search for a song by humming, singing or whistling a portion of it. You can also get result the traditional way by typing.
Licensed digital tracks are available.
Users can also get involved by adding their own singing performances and have them rated by other users.
The name of this new search engine is Midomi. It is in beta. The best way to get a good idea about it is to test it for yourself. Here is a link to it
midomi