At the 'Main' menu go to 'Extras' and then 'Cheats' and press Sqaure and enter the following passwords to unlock the correspondng effect.

Unlock Everything:
Enter the password Kungfoopete

Unlock Freaky Fast:
Enter the password Slingpoo

Unlock Ice Wheels:
Enter the password IceAge

Unlock Touchable:
Enter the password Imtarex

Unlock Vision Switcher:
Enter the password Wearefrozen

Unlock Nitro Addiction:
Enter the password TheDuke

Unlock Slow-Mo Cool, Thrill Cam:
Enter the password Hollywood

Unlock 3 Props in Stunt Creator Mode:
Enter the password COOLPROP

Unlock New Camera Effects and Styles:
Enter the password GFXMODES