All Bikes
In pro quest mode, at the rider selection screen, press up, left, up, down, up, right, left, right, Y.
Play As Slim Jim
At the rider selection screen in Pro quest mode press down (twice), left, right, up (twice), and Y.
Get All Styles
In pro quest mode, at the style selection screen, press left, up, right, down, left, down, right, up, left, y.
Get Movies
Use the characters indicated to finish the game to get these movies:
Dave Mirra - Unlock Dave Mirra movie
Ryan Nyquist - Unlock Ryan Nyquist movie
Amish Boy - Unlock Programmer movie
Slim Jim - Unlock Promo movie