Samurai Jack: The Shadow of Aku Cheats for GameCube

You can unlock different swords by freeing the prisoners. Here's a list of all the ones I know:
Fire sword- Free 30 prisioners in the village level
Ultimate crystal sword- Free 30 prisioners in the forest level
Electric sword- Free 30 prisioners in the mines level
Hope that help's ya!

Crystal Sword:
During game-play press the following combination:
Down on the Right Analog Stick + Up on the C-Stick, A, X, B, Y.
Unlock Backgrounds:
On Normal difficulty complete the game.
Maximum Zen:
During game-play press the following combination:
Hold the Analog-stick Left + C-stick Right, then press X, A, B, Y.
Crystal Sword:
During game-play press the following combination:
Down on the Right Analog Stick + Up on the C-Stick, A, X, B, Y.
Unlock Backgrounds:
On Normal difficulty complete the game.
Maximum Zen:
During game-play press the following combination:
Hold the Analog-stick Left + C-stick Right, then press X, A, B, Y.