Enter your name as the following to activate the cheats:

HANGTHEDJ - access to all cities, all weapons with infinite ammo, Armour, Get Outta Jail Free Card, no police, shows co-ordinates, 99 lives, x5 multiplier and 9999990 points.
THESHIT - access to all cities, infinite ammo for all weapons, 99 lives and x5 multiplier.
MADEMAN - access to all cities, all weapons with infinite ammo, Armour and Get Outta Jail Free Card.
BSTARD - access to all cities, all weapons with infinite ammo, Armour, Get Outta Jail Free Card, maximum wanted level, shows co-ordinates, 99 lives, and x5 multiplier.
GROOVY - all weapons with infinite ammo, Armour and Get Outta Jail Free Card.
WEYHEY - 9999990 points.
CHUFF - no police.
EATTHIS - maximum wanted level.
URGE - access to all cities except Vice City part two.
TVTAN - access to all Liberty City and San Andreas missions.
FECK - access to both Liberty City missions.
CAPRICE - access to all cities.
TURF - access to all cities.
BLOWME - gives co-ordinates.

Enter your name as the following to activate the cheats:

ITSGALLUS - access all levels.
IAMTHELAW - no police.
SUCKMYROCKET - gives you all weapons, Armour and a Get Outta Jail Free Card.
ITCOULDBEYOU - 999999999 points.
STEVESMATES - no police.
IAMGARYPENN - x10 multiplier.
ITSTANTRUM - infinite lives.
NINEINAROW - access all levels.
SUPERWELL - access all levels.
6031769 - infinite lives.
BUCKFAST - Press * on NumPad for all weapons. Press it again for maximum ammo.
PORKCHARSUI - debug mode. Allows you to take screenshots by pressing 'd' during play, saving them in the GTADOS directory as dump#.tga, show your co-ordinates by pressing 'c' and control the zoom by pressing 'k', 'l', '[' and ']'.
HEARTOFGOLD - x10 multiplier.
HATEMACHINE - x10 multiplier