All levels 
At the main menu, press 
Square, Triangle, L1, R2, Circle, X, Triangle, Right, Right, Left 
to unlock all levels.

Bumblebee suit skater 
Select Roach without a hat and enter "BEESUITGUY" as a name 
to get a skater with super stats that can execute huge Ollies 
and 540s.

Snowman board 
Select Axl as a character and enter "ZAXIS" as a name.

Copenhagen board 
Select Cyrus as a character and enter "MARDUK" as a name. 

Rockstar board 
Select any character and enter "ROCKSTAR" as a name. 

Extra points 
Pause the game during a timed run, then hold 
L1 + L2 + R1 + R2 and repeatedly press Circle 
to increase your score 5,000 points at a time.