I even got to look at the Linux Easter Eggs myself, since I had just installed Portable Ubuntu so that I could try-out a Linux operating system as easily as running a program on my Windows machine. The "doctor" hidden in emacs really takes me back. The first time I saw this program I was in college - in the pre-PC days when we all had accounts on the school's Vax mainframe computer. Then it was called Eliza, but the program itself is even older than that.
Video: Watch 10 terrific 'Easter eggs' in action at Computerworld.com
There's some overlap between the two sites. The Computerworld page has video clips of all the Easter Eggs so you can see what they look like even if you don't have the program or operating system involved.