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.
Technologically, what Minebea has done is pretty fancy: they've combined backlights, force sensors, and a new film from a company called Toray Industries to create the world's first "electrostatic capacity type touch panel and a load sensor." Which to me reads "ooo, shiny!" No word yet on when products like this will be commercially available, but when they do I'll be ready with my wallet and a chamois cloth. [Minebea via CrunchGear]