These codes can be accessed in single player mode by hitting 't' and typing 
them or by hitting one of the F1....F4 keys.

eyeofgod - Allows extra level of zoom on lower level machines
saladtossed - Choose level (You will have to go to the load screen after and do
that CTRL h/w thing)
twobyfour - Builds units (ex: twobyfour dragoon)
hermes - Speeds up building of units
donkeys - Anything that shoots a missile shoots jeeps instead of missiles
morningafter - Removes fog of war
gimmiegimmie - Allows you to build everything, even without command center
unclejohn - God mode
chaching - Adds 10,000 to cash total every time it is entered
mrmuscle - Upgrades player's armor
bigsofty - Downgrades enemy armor
coffee - Upgrades player's speed
beer - Downgrades enemy speed
shaft - Upgrade player's firepower
shank - Downgrade enemy's firepower