Unlimited supplies:
Press Select, R1, L1, Select, R3, L1 at the "Extra" menu.
Unlimited health:
Press Left, Right, Up, Down, L3, Square at the "Extra" menu.

Hippy blood:
Press L2, Right, Circle, Down, R1, Select at the "Extra" menu.

Extreme ragdoll:
Press Up, Up, Up, R2, R2, R2, Up at the "Extra" menu.

Low gravity ragdoll:
Press Square, Square, Square, Circle, Circle, Circle, Up, Down at the "Extra" menu.