Infinite health
At the "Extra" menu, press Left, Right, Up, Down, click Left Analog-stick, press X.

Infinite supplies
At the "Extra" menu, press Select, R, L, Back, click Right Analog-stick, press L.

Hippy blood
At the "Extra" menu, press White, Right, B, Down, R, Back.

Extreme ragdoll
At the "Extra" menu, press Up(3), Black(3), Up.

Low gravity ragdoll
At the "Extra" menu, press X(3), B(3), Up, Down.