Oh there are hundreds of google easter eggs.
Here is one for easter from a while back (and took me some time to find it... google'd 'Google easter game').
Not that some things aren't exactly easter eggs though... even though they appear so. A tip I read a while back, if you go to <Linux> - Google Search you can search for only things related to linux. The proof is that if you search "Microsoft" from this page, MS's webpage is not in the results. There's one for MS, Mac, and BSD too.
Also, I remeber I used to use the googlex search before it was taken down (I think somewhere I have a copy of the page...) just because it was bubbly looking. You can see the news about it here.
Google X - for OS X
Uhh... when did VBul start changing URLs to the page names? >__>
thanks to Silverwmoon!