This is one of those "I wish I came up with this" thing. "Song Tapper":http://www.songtapper.com has potential to reduce mankind's cumulative frustration by a few notch.

We all have those moments where a melody stuck in your head but you can't quite place what song it was. And humming it to your friends do nothing but drawing nasty sneer. (especially when he/she now becomes equally frustrated at not identifying it)

And that's the itch Song Tapper is trying to scratch.

I haven't time to test it thoroughly, but it correctly guessed Maroon5's _She Will Be Loved,_ that I tapped in.