High Stepping Into The Endzone:-  This was left undocumented in the manual, but if you are within 10-yards of the end zone and your press the jump button (usually Up-C) your player will high step his way in if there is enough room between you and any defenders. 

Random Stadiums:-  When at the stadium select screen press R or Z for a random stadium. 

Hidden Teams:-  Enter the following codes at the Code Entry screen:

INTHEGAME: To play as EA Sports (publisher) 
HAMMERHEAD: To play as Tiburon (developer) 
BESTNFC: NFC Pro Bowl 
AFCBEST: AFC Pro Bowl 
BOOM: All-Madden Team 
IMTHEMAN: All-Time State Leaders 
PEACELOVE: 60s Greats 
BELLBOTTOMS: 70s Greats 
SPRBWLSHUFL: 80s Greats 
HEREANDNOW: 90s Greats 
TURKEYLEG: All-Time Greats 
THROWBACK: 75th Anniversary Team 
GEARGUYS: NFL Equipment Team 
WELCOMEBACK: 1999 Cleveland Browns 

Hidden Stadiums:-  Enter the following cheats at the code enter screen to get the secret stadiums listed: 

Stadium Code:
OURHOUSE: Tiburon 
EASTADIUM: EA Sports