I saw this post on Boing Boing earlier today, and did a little googling to find out more. Apparently JPL scientists working on the Martian rover projects needed to stay in sync with the Martian solar day, which is 24 hours and 37 minutes long, so they found a local watchmaker to put together some custom watches that ran on this cycle. Here's the story from JPL:
Mars Exploration Rover Mission: Spotlight
The watches themselves are not exactly my taste, but I love the idea of a watch that can keep track of the time on Earth and Mars simultaneously.