In August last year, matttpotter1-ga asked Google Answers for help identifying a song used in epic movie trailers. He was even brave enough to post a movie and sound file of himself trying to sing the tune.
Unfortunately we weren’t able to help him with that particular tune, but there are some resources that can help in many cases.
MusiPedia, which bills itself as the Open Music Encyclopedia, lets you search by keyboard, note contour, singing, whistling or rhythm. The singing search is a Java application for which my browser didn’t recognise the security certificate, so I didn’t try it, but I was able to get it to find Frere Jacques using keyboard search, and Amarillo using contour search.
Then there’s Themefinder, the one to use if you understand musical notation. You can search by pitch, interval, scale degree (“do re mi”), note contour, key and meter. I got good results with this one, except that its repetoire is limited to a few well-known classical composers and a sprinkling of folk music.
Tunespotting lets you search by creating a rough musical score on the screen, or by playing your keyboard as if it were a piano.
[Thanks to Google Blogoscoped and Bobbie7 for these tips]