Tony Hawk's American Sk8land Codes -

Cheat mode:
Successfully complete classic mode the indicated number of characters to unlock the corresponding cheat.

Once character: Create A Skater 
Two characters: : Rail Balance, Manual Balance, and Lip Balance. 
Third characters: Tiny Mode 
Fourth characters: Giant Mode 
Five characters: Matrix Mode 
Six characters: First Person Camera 
Seven characters: Replay Cam 
Eight characters: Turbo Mode 
Nine characters: Always Special 
Ten characters: Paper Tony 
Eleven characters: Hoverboard 
Twelve characters: Nearly Always Ribbon 
Thirteen characters: Ninja Skater 

Successfully complete story mode to unlock the "Legacy Camera" and "Credits" options.

Change ribbon color:
When you turn the DS on, go to "System Settings" at the bottom of the screen (it is the picture of the DS). Go to "Personal Settings" (the picture of a person) and tap the color scheme (the top option, with the squares). Select a color, press A, press B(2), then press A again. Start the DS again, this time starting the game. Anytime you do a spine transfer, flip, roll, etc., there will be a trail of color coming out of your board. That color should be the one you selected.