Tony Hawk's Underground 2

Cheat mode:
Go to "Mini Games" then select the "Stylin" game. Do a manual by pressing Up, Down, then follow the commands that appear on the right side of the screen. You must complete the following levels in Stylin to unlock the corresponding cheat.
Information in this section was contributed by Christopher Graham.

Stud Mode: Level 1
Perfect Rail: Level 2
Always Special: Level 3
Manual Balance: Level 4
Moon Physics: Level 5
Perfect Lip Balance: Level 6
Jet Pack Mode: Level 7
Matrix Mode: Level 8
Turbo Mode: Level 9
Mini Mode: Level 10

Alternately, complete arcade mode with the indicated number of skaters to unlock the corresponding cheat.

Stud Mode: 1 skater
Perfect Rail Balance: 2 skaters
Always Special: 3 skaters
Perfect Manual Balance: 4 skaters
Moon Physics: 5 skaters
Perfect Lip Balance: 6 skaters
Jet Pack Mode: 7 skaters
Matrix Mode: 8 skaters
Turbo Mode: 9 skaters
Mini Mode: 10 skaters

Complete level 2 of the Tagging mini-game to unlock the Graffiti Editor.

Bonus characters:
Go to "Mini Games" then select the "Tennis Shooter" game. You must complete the following levels in Tennis shooter to unlock the corresponding character. Note: To unlock the skaters in arcade mode, complete the "Tennis Shooter" mini-game in story mode at least one time.

Bam Margera: Level 20
Big Foot: Level 40
Bob Burnquist: Level 10
Chad Muska: Level 30
Eric Koston: Level 15
Eric Sparrow: Level 39
Mike Vallely: Level 35
Rodney Mullen: Level 25
Tony Hawk: Level 5
Wee-Bones: Level 41

Hint: Letters:
You need to collect the letters "COMBO" all in one trick. This completes a task. The best way to do this is by a grind. Press A to grind.
Information in this section was contributed by Christopher Graham.

When Tony asks you to get the combo letters in Boston and Berlin, (levels 1 and 2), do a Runout. You can then run and get all the letters. Be careful -- if you fall in a bowl you cannot get out without getting back on your board, which ends your combo. Once you have all the letters, press B to get back on your board. You will then have completed the goal.

Hint: Easy points:
The best way to get points is to enable the "Moon Physics" cheat.

Glitch: Wrong dialogue:
In the first level in Boston, when you talk to the Roller Blader for the third time he says" Manual the Small Road" instead of "Tiny Road".
Information in this section was contributed by Abel Ramos.