Games I could see doing well on the 3DS include, but are no means limited to...
- F-Zero. Seriously, this NEEDS to happen. Going through a corkscrew at over a thousand miles an hour in full 3D online with your friends? Which part of that sounds like a bad idea? Most probable reason why it hasn't happened yet: Nintendo are such health and safety gimps they're afraid the game will give us motion sickness.
- Pokemon Snap. What's most insulting is that the technology clearly exists in the form of upcoming game 'The Hidden', which superimposes ghostly images over the AR camera's feed, allowing us to interact with them. Replace the ghosts with pokemon (all of them, do it properly or not at all), allow us to throw bait and stuff like in the 3D Pokedex, give us the facilities to share photos via streetpass and upload them to share with the world via wifi, run competitions to get the best shot of the rarest creature. Hell, I don't even play Pokemon any more but for that I'd make the exception. That's a system seller right there.
- Afterburner/Outrun. Two of my favourite games of all time, I love the speed, the constantly changing surroundings, etc. It'd work so well with the 3D.
I have a lot more to list but I gotta go out for a bit so I'll pick this up again later.