Try

http://trillian.mit.edu/~jc/music/abc/FindTune.html

This is a phenomenal resource containing thousands of tunes in many versions and keys. The great thing is that every tune is available in the following formats:

ABC TXT PS EPS PDF PNG GIF MIDI

MIDI will play the tunes if you can't read music. Looking at the dots, while listening to the MIDI will teach you how to read music.