Unlimited supplies:
     Press  Back, R, L, Back, click Right Analog-stick, press L at the
"Extra" menu.

Unlimited health:
     Press  Left,  Right,  Up, Down, click Left Analog-stick, X at the
"Extra" menu.

Hippy blood:
     Press White, Right, B, Down, R, Back at the "Extra" menu.

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

Low gravity ragdoll:
     Press X, X, X, B, B, B, Up, Down at the "Extra" menu.