Check out the Song Tapper, where you can tap out the rhythm of the lyrics to a song on the space bar of your keyboard, and it will determine the title. You can add rhythms to its database so that it can recognize more tunes.
Not always accurate– it recognized “Daytripper” by The Beatles when I tapped it out, but thought “Iron Man” by Black Sabbath was “Fur Elise” by Beethoven. However, this database will definitely improve with more input by its users. It was shown in demonstration at a recent artificial intelligence conference. Geoff Peters is one of the group who put this together.
When I worked at a music store many moons ago, there was no end to customers who would ask, “Do you have a recording of this song? It goes like this…” and would hum or sing the tune for us. Maybe this tool will help towards this end.