Yeah, get the Donkey Kong Country trilogy. DKC on GBA is
craptastic compared to the SNES original. Seems all the really good fighters and RPG's have been mentioned (oh wait, try Illusion of Gia, too). Try Bubsy for a fun, happy happy joy joy platform game. Stay the hell away from Bubsy 2 though.
Super Castlevania, Super Ghoul's and Ghosts, Lost Vikings, TMNT in Time, Plok!, Clay Fighter, Mario and Wario (was this released in the US?), EVO, Smash Tennis, Claymates, Earthworm Jim/2 and.. Erm... Lots more. Check 'em out.