Well I happened to stumble over this fancy shmancy 404 page today at GitHub, and I must say it is simplistic, yet VERY impressive (maybe its the whole starwars thing) but I really like the simple 3D effect that is created by using layered images.

Try it yourself, go to: https://github.com/thispagenotfound

And move your mouse around the 404 ‘image’ you will be pleasantly surprised that the effect is the images move to reflect your cursors position, thereby creating the look and feel of 3D movement.

I really like finding these little gems on 404 pages, or 500 errors (like common on Woot), or even Googles “Aww! Snap!” message when it crashes.