While Sensitive Object sounds like a gift shop for ladies who love kitties and angels, it is, in fact, a French company that creates interface systems based on temporal reversal. Apparently if you tap on an object at any point waves propagate through the object in different ways depending on the position of the tap. I don't know. Don't ask me. Anyway, Sensitive Object is working on new UIs based on this phenomenon, which means you can have keyboards with no moving parts.

Product Page [Sensitive Object via Module-Records]