Type in the following at the specified screen. You'll see a small logo to confirm. Some of these
codes will only work if you have the latest patch: 

During Play
check       Auto-checking     
grab        Auto-holding
injury      Cause an injury   
flash       Camera flashes   
mantis      Long arms, legs, and necks    
quickftr    Faster players    
penalty     Powerplay situation    
big fight   Huge fights  
spots       Pre-game spotlight    
bloody      Bloody fights
awaygoal    Away team goal
homegoal    Home team goal     
nhlkids     Little players
victory     Fireworks 
zambo       Zamboni comes out   

Credits Screen 
buffed      Big players    
gulliver    Big goalies    
headbone    Big heads    
massrink    Big rink    
night       Dark arena with spotlights 
squeaky     High pitched commentary    
barrywhite  Low pitched commentary    
warp9       Fast game    
slomo       Slow game     
zerog       No gravity for puck