Full Armor for Version 1.1
If you have the 1.1 update (came out 27/06/02), the full armor code, turtoise, has been changed to tortoise.
Cheat Codes
Main Cheats:

GUNSGUNSGUNS = Weapon Cheat
IFIWEREARICHMAN = Money Cheat
GESUNDHEIT = Health Cheat
TURTOISE (or TORTOISE, in 1.1) = Armor Cheat

Weather Cheats:

SKINCANCERFORME = Nice Weather
ILiKESCOTLAND = Fog Thickness Level 1
ILOVESCOTLAND = Fog Thickness Level 2
PEASOUP = Fog Thickness Level 3

Pedestrian Cheats:

ITSALLGOINGMAAAD = Crazy Peds
NOBODYLIKESME = Peds Want To Kill You
WEAPONSFORALL = Peds Pack Heat (Carry Weapons)
CHITTYCHITTYBB = Flying Cars

Other Cheats:

MOREPOLICEPLEASE = Wanted Level Up
NOPOLICEPLEASE = Wanted Level Down
GIVEUSATANK = Spawn A Tank
ANICESETOFWHEELS = See-Thru Cars
CORNERSLIKEMAD = Better Driving Code
TIMEFLIESWHENYOU = Fast Gameplay
ILIKEDRESSINGUP = Change Character
BANGBANGBANG = Blow Up Cars Around You

Unknown Cheats:

NASTYLIMBCHEAT = Nastier Limb Removal?
MADWEATHER = Time Speeds Up?
BOOOOORING = Unknown (Time Slows Down?)