I love to see a great 404 page when things go wrong. The twitter fail whale has become a great example of how to make a statement on an error or 404 page. It has become an art of both design and communication when you do something like a 404 page.
Here is a great list of interesting and great 404 error pages.
The fact that the Huffington post wrote an article on this topic means that the common non-technical person also understands what a 404 (page not found) error is. Or at least they know what it means to them
Unfortunately I’m not that up on design and will have to update jimiz.net 404 error page.