Sure, we all know what Easter Eggs are. But no, I’m not referring to the decorated eggs used to celebrate the Easter season. What I am referring to is the Easter Egg of the virtual kind – the hidden messages, the unusual behavior, the undocumented features found in software programs and applications generally intended as a joke by its authors/creators.

For example, if you type about:robots in Firefox v3.0 you will get a special message. Also check out what about:mozilla and about kitchensink do. Although the latter is not technically an easter egg, it’s worth checking out.

Google are themselves masters at easter eggs & hoaxes. PCWorld.com survey some of their better attempts.