On Friday I came across The 101 Coolest Easter Eggs Hidden in Your Software, DVDs and Video Games. Although I haven’t hunted down more than a handful of them, some of them appear to be fun (OpenOffice.org: Star Wars Game), some are funny (Firefox: Firefox’s Revenge for IE5′s Joke), some are lame (Winamp: Spinning Fish), and some are quite intriguing (IRIX: Hidden Recipes in Release Notes).
That’s all IMHO, of course.
Happy hunting!