Well, I might as well join in.

jjmoo - Turns Jazz into a Cow
jjfish - Turns Jazz into a fish and raises the water level
jjjumpoffacliffanddie - Kills Jazz, except with a really cool death sequence
jjcheat - Instantly crashes the game with error message "OMGHAX!"
jjnumberjj2 - Plays a random quote from #jj2 on irc.quakenet.org
jjwallclimb - Allows you to wallclimb by yourself.
jjapan - Changes the language to Japanese.
jjwheeesplat - Same as jjjumpoffacliffanddie.

That's it, I'm all out of ideas here.