ApertureScience.com [Easter Egg]
The various grafitti in Portal can help you crack the code for the website www.aperturescience.com. Go to the website (Shockwave Flash) and type in the command LOGIN.

The user name is CJOHNSON and the password is TIER3. Once you are in, you may type in HELP for a list of valid commands.

You should also be able to login to aperturescience.com with the username GLADOS and the password PORTAL, as well.

Edit: It actually doesn't matter what name you login with. You can login with any name you want. It's the password you insert that's important.

Edit: After logging in, type at the prompt thecakeisalie. Doing so will unlock some secret messages for you to view.



All Levels (Half-Life 2)
Description: Unlock all of the game's levels, insert the following button sequence cheat code on any stage while playing the game:
Left, Left, Left, Left, L1, Right, Right, Right, Right, R1

Restore Health
Description: Restore your health by 25 points
How to: Insert the following button sequence on any stage while playing the game:
Up, Up, Down, Down, Left, Right, Left, Right, Circle, X

Restore Ammo
Restore ammunition on your currently-equipped weapon to maximum.
How to: Insert the following button sequence on any stage while playing the game:
Triangle, Circle, X, Square, R1, Triangle, Square, X, Circle, R1