Extra Health:
When your health is low, go to a sign post and save your game. Next, hit start and choose load. Reload the game and you will have full health

Bonus Weapons:
Start a new game. Then, when the pigs are dancing (loading screen) enter:
Hold R1, Select, Right, Left, Down, X, Circle, Start
After the game has loaded push Start to see the new weapons.

Tomba's Different Hair Colors:
Goto the options menu screen and: Hold R1, L1, Select, and Square. While doing this press Left, Down, Right, Up, Up, Right, Down, Left