Face it: from time to time, people are going to to type in something wrong when it comes to your web site and get a 404 error on their browser (or a 500 error if you have a J2EE server down). Why not give them something interesting, like this:
From the always interesting siteReflectionOf.Me
Smart People I Know 
Hi this is a great idea. I did the same because it is boring to see a regular 404. My idea was to have a funny 404. If you want you can see mine under http://www.olafernst.com/xyz