NFL GameDay 2003 Cheats

Bonus teams:
Push Circle in the team selection screen to get a Super Bowl team. Push Circle, Cirle in the team selection screen to get an All-Star team.

Customize your playbook:
It is important to utilize your play editor. You can customize plays for your star player so that you can effectively utilize his talents.

Picking plays:
When the computer selects its play, you can select an offensive play / defensive play accordingly (taking into account their selection). In this 989 Sports title this trick becomes even more useful. 
User Cheat by BillSunshine

Have your player names announced:
By making a player with a last name of someone who is already in the game. If done correctly your player will have his name announced while playing the game.

NFL GameDay 2003 Code Breaker Codes

NFL GameDay 2003 GameShark V2 Codes (NA)

NFL GameDay 2003 Pro Action Replay Codes (NA)