This clock design by the alternating caps friendly YOnoBI takes the simple idea of mirrors to create a unique effect. The actual clock lays flat on a base painted with Vermillion lacquer. An angled, upper layer is coated with a translucent lacquer that will reflect the digital numbers from the base, and that is it. It obviously doesn't work so well in direct sunlight, but it would be one hell of a cool effect in pitch, or near pitch darkness.
The official name of the clock is "dancing on the water," which is a little too design-y for my tastes, but I would suppose the reflection makes the digital display appear to be dancing on the water (or just floating in the air). Yukio Hashimoto is the mastermind behind the floating/dancing time concept.