Easter eggs (and it's nearly Christmas!)

Easter Eggs is a quirky name that techies give to messages or features hidden inside software applications or games. Most of them are amusing, and some are even useful (though being useful is probably the last thing the authors intended). The How-to Geek has a list of some of the better-known ones. There's even a website devoted entirely to the genre, and the range is quite mind-boggling. This could become addictive.