Error Code 404, or the page you've requested is not found.
Some folks get pretty creative with these.
This one is from The Discovery Website
Greg
This probably wont mean a thing to folks in the US, but at one time a Liverpool FC fan page had this little dig at their Mersey-side rivals Everton FC on their 404 page:
"The page you are looking for - like Everton's European Cups - does not exist"