http://www.eeggs.com/
This page tells you all about easter eggs in software, music, movies, etc. Here is their definition of it - "any amusing tidbit that creators hid in their creations." - meaning, not just a new level, but anything from the disco music in Warcraft 2, to the hidden D&D movie in Summoner. Of course, this is just my, Saintholgi's and the owner of the site's opinion, and you can believe whatever you want.
[This message has been edited by Hans (edited January 27, 2002).]