Deus Ex Easter Egg - Matrix Mode, Dance Party

First, you must enable the cheats mode as described in http://www.eeggs.com/items/16769.html (I hope the link doesn't change in the future).

Start a new game (or load one).

Then, go to the main menu and select "Credits".

While the credits are playing, blindly type "thereisnospoon". You'll hear a click for every key you press, but be careful not to make a mistake or you'll have to start over.

Then go back to your game, and voilà: everything is made up of scrolling green numbers, like in the movie!

Another egg: (cheats must be enabled, but no game needs to be running, i.e. you can do this immediately after the startup of DX) in the credits screen, this time you type "danceparty". Enjoy!