Mini-games:
To unlock some mini-games (the ones from Moto GP and a couple others), go into 
options menu and watch the text (not video) credits. Scroll down until you get to 
the credits for the mini-games. When it appears onscreen, press A. To confirm 
correct code entry, the screen with the "Mini Games" title will have the "A" 
in "Games" change to resemble that found on that controller button.

Floating bike mode:
Edit the logo on a custom bike to read kingpin. 

Legends mode:
Unlock Challenges 62 through 66. Challenge 67 will be legends mode. 

Valentino Rossi 
Earn an overall total of 1000000 points in stunt mode 

Turbo 
Earn 275 championship points to unlock the Turbo cheat 

Tohru Ukawa 
Get an overall total of 750,000 points in stunt mode to unlock Tohru Ukawa 

Sheridan 
To unlock the Sheridan track complete all the challenges in championship

Season Highlights 
Finish first in any track to earn it's highlights video 

Saturate 
Earn 300 championship points on rookie to unlock the Saturate cheat 

Pop Video 
Earn 375 championship points to unlock the Pop Video cheat 

Max Biaggi 
Get an overall total of 500,000 points in stunt mode to unlock Max Biaggi 

Edgy 
Earn 325 championship points to unlock the Edgy cheat 

Carlos Chera 
Get an overall total of 100,000 points in stunt mode to unlock Carlos Chera 

Alex Barros 
Get an overall total of 250,000 points in stunt mode to unlock Alex Barros