Unlock Everything:
At the main menu, quickly press Up, Down, Up, Down, Up, Down, Up, Down, Up, Down, Left, Right, Left, Right, Left, Right, Left, Right, Left, Right.

Unlock All Levels:
At the main menu, press Square, Square, Square, Square, Circle, Circle, Circle, Circle, Triangle, Triangle, Triangle, Triangle, Square, Circle, Triangle. A voice will say "Travel Visa Approved" to confirm.

Unlock More Boards:
At the main menu, press Up, Up, Left, Left, Right, Right, Down, Down, Up, Left, Right, Down, Up, Left, Right, Down. A voice will say "You got all the boards...or did you?" to confirm.

All boarders:
Rotate the Right analog-stick clockwise fifteen times.

All gaps:
At the main menu, press R1, L1, L2, R2, R1, L1, L2, R2, R1, L1, L2, R2, R1, L1, L2, R2.

Thanks to Revolution readers Andrew Long, splat and BarnumBail!