1) Cockpit based games. Flying a plane, or spaceship, in VR is immensely better than on a screen. I get nauseous in car racing games but, my friends who do not, rate them as best simulated driving experience ever.
2) Room scale games. Here, I have no idea wich ones. It is a complete green field in terms of gaming. There are some great concepts, like Fantastic Contraption or the "space invaders"-like game in The Lab (with hilarious results for non-playing spectators), but all in all, it's something that is not explored yet and shows fantastic promise.