Tony Hawk's Pro Skater 3

Unlock All FMVs:
Go to the Options/Cheats menu, enter "peepshow". To turn them on, pause while playing and enter the Cheats menu.

Unlock all characters:
Go to the Options/Cheats menu, enter "yohomies"

Hidden area, Tokyo:
The tokyo area has a cool hidden area. When you start look up and to the left you should see a circlular neon sign with two wires one on each side. Grind one to make the sign unstable and it will fall crashing down and opening the secret neon rail area with the suspened waterfall.

Unlock Warehouse level:
Complete all the goals in the game and get gold medals in all three competitions three times in career mode with a created skater.

Unlock features:
To unlock the different features, complete all goals and get gold medals in all three competitions in career with a different skater each time. Do this the indicated amount of times for the different features.

1 time: Play as Darth Maul
2 times: Play as Wolverine
3 times: Play as Officer Dick
5 times: Play as Private Carrera
6 times: Burnside level from Tony Hawk's Pro Skater
7 times: Ollie the magic bum
8 times: Play as Kelly Slater
9 times: Roswell level from Tony Hawk's Pro Skater
10 times: Play as Demoness
11 times: Snowboard mode
12 times: Infinite specials
13 times: Perfect balance for rails
14 times: Super Stats
15 times: Huge skater
16 times: Slow-motion mode
17 times: Perfect balance for manuals
18 times: Small skater
19 times: Moon physics
20 times: Expert mode
21 times: First person view

Unlock All Cheats:
Go to the Options/Cheats menu, enter "backdoor". To turn them on, pause while playing and enter the Cheats menu.

Pirate Ship:
In Skater's Island, grind the pirate flag between the half-pipe and the set of bowls to open up the outside level (where the last stat point is) and gain access to the pirate ship.