I spent hours at college playing Donkey Kong Land - absolutely brilliant platformer with great gfx to boot.
Tomb Raider was pretty good - very simlar to prince of persia in some ways but still had the tomb raider feel. Personally, I don't think the GBC had any standout titles.
Denki blocks - Get's repetitive but has that 'must have another go' vibe.
Super Monkey Ball - Surprising well executed and faithful to the Game Cube version.
Chu Chu Rocket - almost identical to the DC versionm it's a little gem of a game.
Crash Bandicoot - Pure 2D platforming with 3D sub games.
Sonic The Hedgehog - Again, great 2D FAST platforming - the sonic sprite is well animated.
Doom - Say no more. It's almost all there and has decent 3D speed.
Wario Ware - This game is so damn addictive. A series of simple mini games that only last a couple of seconds but it's done in such a way that they come at you thick and fast and the adrenelin starts pumping. Brilliant!!!!