Beat the game on any difficulty. When you start a new game, scroll the list down to Allessia Faithhammer, then push down for Drizzt.

Beat the game on Extreme Difficulty. When you start a new game, scroll the list down to Allessia Faithhammer, push down for Drizzt and down again for Artemis.

Have 2 players going at the same time, and go into town. One character drops whatever they want to duplicate. Import the character that just dropped their stuff - they will have all the things that they just dropped, plus the ones on the ground. Pick up the stuff, sell the duplicates, then save and repeat as necessary.

From within the game:
PS2: Press and hold L1 + R1 + Triangle + Square + Circle + X. While still holding them, press L2.
Xbox: Press and hold Left trigger + Right trigger + Y + A + B + X. While still holding them, press the White button.

This cheat will set your character to level 10, grant 45 feat points, and 500,000 gold pieces. It can only be used once per session, and if your character is already level 11 or higher, it will be lowered back to level 10 (This cheat does not completely work on Drizzt or Artemis - you will receive the gold, but the level and feat points will not change.)

PS2: Hold down L1 + R1 + Triangle + Square + Circle + X. While holding them, press START.
Xbox: Hold down Left trigger + Right trigger + Y + A + B + X. While still holding them, press the Start button.

This opens a cheat menu that allows you to toggle Invulnerability and warp to different levels.