Unverified. Go under Extras into the Cheats-Menu and enter following keys.

Unlock Levels .... Black, White, Black, White, Left Trigger, Right Trigger, Start
Unlock Art Gallery .... Y, A, Black, White, Y, A, Start
Unlock Movie Gallery .... Left Trigger, Left Trigger, Y, A, Left Trigger, Right Trigger, Start
Fully Loaded (Unlimited Ammo) .... White, Black, Y, Black, A, White, Start
Bulletproof (Infinite Health) .... Left Trigger, Right Trigger, Y, Y, Right Trigger, Y, Start
Adrenaline Rush (Infinite Adrenaline) .... A, Left Trigger, Y, A, Left Trigger, A, Start
Magic Bullet (One Shot Kills) .... Right Trigger, Black, Y, A, Right Trigger, A, Start
Battering Ram (Instant Crash) .... Black, Black, A, A, Y, White, Start
Time Out (Infinite Timer) .... Right Trigger, Right Trigger, White, Y, A, Black, Start