Easter Eggs in Web Sites?

cwikla asks: "Back in the .COM days, I worked at eGroups, now owned by a larger Company. During my time I added a couple of easter eggs to the site, which I was reminded of while watching Being John Malkovich this weekend. I checked, and ones sort of still there. If you append malkovich=1 to a message URL it would turn the message into 'malkovich' mode. It sort of still works, but over time I guess the code has been a changin' so it's kind of spotty. Oh, there are others that still are in there, but where's the fun of telling all the secrets? Any other folks done anything equivalent, especially on mainstream sites?"