Cheat Codes (DEMO VERSION)
Enable the console from the game’s in-game options. Hit the tilde key (~) to drop the dev-console. Type “seta thereisacow 1337″ and then press ENTER. Type spdevmap bog_a and then press ENTER. This will start the demo with cheats enabled. When playing, drop down the dev-console and enter the following codes and hit ENTER to activate or toggle them.

give all: Access All Weapons
god: God Mode
noclip: No Clipping Mode
notarget: Enemies Ignore You
give ammo: Full Ammo
jump_height #: Adjust Gravity (Default = 39)
timescale #: Adjust Time (Default = 1.00)
cg_LaserForceOn 1: Add Laser Sight to All Weapons

Cheat Codes (RETAIL GAME)
Enable the console from the game’s in-game options. Hit the tilde key (~) to drop the dev-console. Type “seta thereisacow 1337″ and then press ENTER. Type spdevmap bog_a and then press ENTER. This will start the game with cheats enabled. When playing, drop down the dev-console and enter the following codes and hit ENTER to activate or toggle them.

give all: Access All Weapons
god: God Mode
noclip: No Clipping Mode
ufo: No Clipping Mode
notarget: Enemies Ignore You
give ammo: Full Ammo
jump_height #: Adjust Gravity (Default = 39)
timescale #: Adjust Time (Default = 1.00)
cg_LaserForceOn 1: Add Laser Sight to All Weapons
give - Gives you an item. put all for all weapons
demigod - God mode but your screen still shakes
r_fullbright - Way easier to see stuff this way
cg_drawGun - Get rid of your gun
cg_fov - Lets you zoom with any gun

Unlock all cheats without collecting intel
Just go into the folder:

C:\Program Files\Activision\Call of Duty 4 - Modern Warfare\players\profiles\profilename.

Then open config.cfg and search for “cheat_points”. Then just change the number next to it to “30″. Voila all cheats unlocked.

Hints
NOTE: As their name suggests hints are not exactly Call of Duty 4: Modern Warfare cheats, and are usually just simple (but very useful) tips on how you can unlock secret level, features, find hidden areas and such. Hopefully these will make playing Call of Duty 4: Modern Warfare even more entertaining.

Epilogue Mission
If you sit through the credits at the end of the game, there’s one more mission available.

Epilogue Mission: View the ending credits to unlock one final mission

Unlock Arcade Mode and Cheats Option
After completing the game, these options are automatically awarded to you.

Arcade Mode: Complete the game on any difficulty.
Cheats Menu: Complete the game on any difficulty.

Originally from ActionTrip