Press Alt-\ anywhere in the game, then enter these codes:

VERSION
Version info

VERSIONID
Gives you a little more information

TURBO
Move faster

HELLO
A bit weird, this one

GARBLE
Ungarble the cheat codes

SUPERUZI
Gives you the super Uzi

FIREPOWER
Gives you all weapons

NEXTMISSION
Advance to next mission

ICANTSEE
Gives you infra-red vision

WHOAMI
Shows your handle

COUNTERS
Current map position

BANDAID
Gives you lots of health