In 2002, Lucien Vouillamoz approached his friends in the start-up world with an idea: He wanted to create a clepsydra – an ancient Greek device that showed time with flowing water – for the wrist. A strange concept, but Vouillamoz rallied his friends. "When you create a paradox, you create interest and innovation," he says. The HYT H1, which took 10 years to create, is a marriage of old-world watchmaking and high tech. It features a tube containing two liquids that mark the hour; the liquid resets itself every 12 hours, draining into a small, hidden reservoir. Pistons push the liquid through the watch, offering a unique view on the passage of time. [$45,000; hytwatches.com]