It seems there are more than a handful of web wonks here on CAKE. I am more of a designer than a coder but thanks to Wordpress (I know some of you are hissing already), I can find all the appropriate building blocks and produce <$10K websites for small businesses. I have no idea how you professional coders build in easter eggs, but, in my own amateur way I embrace customizing the whole 404 page thing. Most of my customers have no idea that I implement this and depending on the customer and their audience determines how funny I can be. But, here is the image I use for my company 404 page. Do you have a fav?