Just type in:

 CAN'T TOUCH THIS     Unstoppable ball carrier
 SUPERMAN             Super dives and jumps
 READY TO FUMBLE      Press "L" to cause a fumble when playing a game
 ALOHA                Unlock Pro-bowl stadium and AFC and NFC Pro-bowl teams
 HOWDY                Unlock Reliant Stadium (Texans') for practice and exibition
 SHAKE IT UP          Weather in domed stadiums
 SHOW EVERYONE        Shows everyone
 SCOREBOX             Control scoring