Easy win
If you are losing a game in world class mode, pause the game. Choose "Side Select" from the pause menu, then move your controller under our opponent's name. Then, score your own goals as that team.

Fake cross over
While kicking, hold L2 + R2 and your player will fake a cross over.

Better passes
Press Square instead of X to pass and the ball should go over defenders. Note the arrow color to judge what a pass will do. White arrows indicate the pass will go through. Blue arrows will indicate that a pass will be blocked or stolen. You can also press L2 and/or R2 to curve the pass. Press the Left Analog-stick to control the passing direction. You can also use the D-pad to take control over passes.

Cheat mode
At the rewards screen, press Square to access the cheat options that can be unlocked during game play:

Big Melon
Win the European Champions' Cup. This cheat gives all players big heads.

Crazy Ball
Win the EFA Trophy. Press Square to make the ball move in a crazy path when it is passed.

Stay N Play
Win the European Championships. The ball will always rebound from the touchline.

They All Fall Down
Win the Copa America. Your players will all fall down if the ball remains in possession for too long.

Eye Catcher
Win the Gold Cup. The ball will be giant sized.

Scrimmage
Win the Champion's League (ECC) and whatever League Title (i.e. Premeireship) under professional mode. All the lads are gone out for a pint and only five players remain. Its indoor footie at its finest. There are also no bookings.

From Outside
Win the Champion's League (ECC) and whatever League Title (i.e. Premeireship) under professional mode. From outside the 18 yard box, if you put the ball in the onion bag, the goal is worth two.

Bonus tournaments
Win the following World Cup qualifications to unlock the corresponding bonus tournaments:

AFC: Asians Nations Cup
CONCEBOL: Gold Cup
CONCACAF: Copa America
UEFA: European Championships (Euro 2004)
Complete all rewards except the last locked one to unlock the FIFA Confederations Cup.

Pictures
Win the following events to unlock the corresponding player picture:

AFC World Cup qualification: Myung Bo Hong
UEFA World Cup qualification: Francesco Totti
CONMEBOL World Cup qualification: Roberto Carlos
CONCACAF World Cup qualification: Ruud Van Nistelrooy
EFA: Nuno Gomez
European Championship Cup: Iker Casillas
European Championship: Thierry Henry
Copa America: Henrik Larsson
Gold Cup: Thomasz Rodzinski
FIFA Confederations: Steve Marlet