Call of Duty [cheats] Create a shortcut and edit the properties of it and add this after all the other stuff: "+set monkeytoy 0 +set sv_cheats 1" (without the quotes) 

Start the game and press the tilde sign (~) to open the console. 

Note: If after you type one of these codes in the console it tells you that "sv_cheats are read only", then try typing this into the console: setrandom sv_cheats 1 

Enter some of these commands:
give - Gives player an object ("give mp 40", etc.) 
give health - gives you full health 
god - Invulnerability 
notarget - The enemies won't shoot you 
noclip - Walk through walls and such. 

-from normanic