I will try to pick ones out that arent so obvious, as everyone else will cover those
SNES - Rock N' Roll racing (AWESOME racing game, great graphics, the music is unbelievable, expecially if you like rock music)
SNES - Donky Kong County 1 & 2 (3 sucked. 1 was great and 2 was absolutley brillant)
SNES - TMNT 4 (excellent excellent game)
SNES - WWF RAW (if you like wrestling that is
)
NES - Guerlla War (a great top down shooter from the gods at SNK)
NES - NES Play Action Football (if it wasnt for NFL2K this would be my favorite football game ever)
NES - Super Mario Bros. 3 (obvious choice, but this is the greatest mario game of them all)
NES - Super Dodgeball (awesome!)
NES - Little League Baseball (yet another awesome game from the gods at SNK. #2 baseball game ever for me)
NES - Blaster Master (great tank sidescrolling game. You can even exit the tank and play in these cool topdown views with your guy. Great music too)
So so many more but I'm drawing a blank.