Cool Leaf is an input system that's perfectly flat, and wonderfully mirrored. A Japanese company called Minebea pioneered it, and they're demonstrating it with a keyboard, calculator, and remote control that are complete key top-free.

The immediately apparent benefit—other than the crazy-futuristic look— is that the devices would be easy to clean: no keys for dust or crumbs to get stuck behind or under. The reflective surface also looks great, although I'd be worried about smudging.