Since the codes for consoles had to be done or by entering phone numbers or gamepad combinations, which is cumbersome to say the least, some sites already released pc codes, which only need to be entered in console mode, which you activate by pressing TILDE ~ key
Known and working codes:
Invincibility:
press ~ key then type PAINKILLER to be invincible for five minutes. You must enter the code again after five minutes to reactivate invincibility. Note: This code does not make vehicles invincible.
Recharge special ability: POWERUP
Faster run: CATCHME
Flaming bullets: INCENDIARY
Explosive Melee Attacks: HOTHANDS
Slow-motion aim: DEADEYE . The code can be entered up to three times to increase its effect. Enter it a fourth time to disable the code.
Moon gravity: FLOATER . Enter a vehicle after enabling this code to experience less gravity.
Spawn Comet (two door sports car): COMET
Spawn Limo (limousine): VINEWOOD
Spawn parachute: SKYDIVE
Spawn Buzzard (small attack helicopter): BUZZOFF .The Buzzard is a helicopter with missiles and guns. It must be spawned in a large enough area for it to appear, or it will not spawn.
Spawn PCJ-600 motorcycle: ROCKET
Spawn Rapid GT (two door sports car): RAPIDGT
Spawn Sanchez (dual-sport dirt bike): OFFROAD
Spawn Trashmaster (garbage truck): TRASHED
Skyfall: SKYFALL . This cheat code spawns you in the air for a skydive free fall. You can glide for a long time. However, it does not allow you to use the parachute. Thus, you will usually die at the end of the free fall. It is possible to survive, but you will have very little health remaining. The best way to survive is to do a direct vertical faceplant. If you can survive the fall, this cheat is very useful for fast traveling around the map.
Drunk mode: LIQUOR
Slow-motion mode: SLOWMO . The code can be entered up to four times to increase its effect. Enter it a fifth time to disable the code.
Change weather: MAKEITRAIN . Each time the code is entered, it rotates through sunny, clear, cloudy, smoggy, overcast, rainy, thundering, clearing, and snowing weather.
This are not all the cheats, more is on gta5cheats.com
I just took a few and tested them, feel free to add more
SIDENOTE: entering cheat codes normally disable achievements.
[Edited by jackbig, 4/14/2015 9:45:01 AM]
[Edited by jackbig, 4/14/2015 9:54:08 AM]