On VC probably Ogre Battle 64 (N64), some C64 games (Impossible Mission series), or some co-op multiplayer curiosity like Crack Down (MD) and Dungeon Explorer (TG).
On WiiWare probably going to add some of the high rated games I still miss: Rage of the Gladiator, LIT, Zombie Panic in Wonderland, and Space Invaders Get Even. Maybe a new racing game as well, but I need more impressions (a demo would be best) for Rush Rush Rally Racing and TNT Racers. Both seem to be really good.
Anyways, it's just as fun to play now as it was back then, IMO.