McGill University's Yon Visell and colleagues have been developing and presenting on a system for adding augmented reality effects to floor tiles by simulating (using haptics and audio feedback) different walking-surfaces, such as pebbles or grass. It's a clever system and I can believe that it would substantially and subtly improve the illusion that you're in a different place, or two places at once.
The modular "haptic" floor tiling system is made up of a deformable plate suspended on a platform. Between the plate and platform are sensors that detect forces from the user's foot. And the plate can give off vibrations that mimic the feeling of stepping on different materials. A top-down projection and speakers add visual and audio feedback.
Yon Visell, a researcher at McGill's Center for Intelligent Machines and first author of the paper, says the tiles could be used "either for human computer interaction or immersive virtual reality applications."
The floor could even function as a giant touch-screen controlled by feet, Visell suggests, acting as a way of navigating a giant map on the floor of a building lobby or public square. He says it could also be used in gaming and entertainment, adding more interactivity.
(via Beyond the Beyond)