It's not quite as awesome as The Shining shown backwards and forwards at the same time but all six Star Wars movies at once is pretty good. At least get through the first minute to hear the main title themes piling on top of each other as they are slightly delayed by a few seconds on each film.
Here's a quick little live version of the theme played by Buckethead who then transforms his guitar into a blaster and something sounding a little like R2D2.
Buckethead -- Star Wars Main Theme [Live] [mp3]
You can find the full video here and buy Buckethead's albums here.