There have been numerous versions of the song American Pie, rewritten to be about Pi instead. The one I've seen go the furthest in terms of Pi digits, though, is Alex C. Thompson's version. A few viewings, and you'll know Pi to 30 digits!

If you're more ambitious, you can try this page which will help you sing it up to 191 digits! The music from this page comes from Hard n Phirm's Pi video, which is also available on Google Video and MySpace.

Video Formats:
Google Video
MySpace
YouTube