Ok, back on topic. I had a DS Lite a while ago, but I wasn't so impressed with it. But there's a designer at my work who used to work for Nintendo, and still does promotions and stuff, and he was showing off his 3DS to us, and the AR stuff that it can do is pretty awesome.
I don't know if it's a concept thing or a released game, but you can eg. look at your desk though its camera, but if you put a card on the desk it kicks off a program, and you see your desk swell and burst, and a dragon pops out and you have to shoot at it, and as you move around with the camera, it changes the perspective.
Pretty cool stuff