“Want to have a little bit of fun with your Gnome desktop? here are a few easter eggs for you.First, hit the Alt-F2 keys together to bring up the Run Applications dialog.
Type “gegls from outer space” (sans quotes) and hit the enter key. You should get the below game, a la space invaders.
Next, try typing “free the fish” (sans quotes) into the Run Applications box. You’ll get Wanda on your desktop.”
Source: http://www.arsgeek.com/?p=1996