I recently saw this clock
online. It's really cool, because you can turn it to rest on any of its twelve sides, and it displays the correct time for somewhere in the world- the city listed at the top. But I thought that the user interaction was unclear- do you turn the city you want to the top, or the bottom? It's got enough sides that you have to double check to make sure your city is right on top. And they're selling it for over a hundred dollars...
It's not really that useful if you're a world traveler- you have to take the minute hand off or it's wrong every time you turn it. But the hours are right, so it's good for if you're doing international business, or have friends overseas that you want to contact. Actually, I was considering making a version that left off the cities and simply displayed the names of my wide-spread family members so that we'd have an easier time discussing when to Skype call.
**a further disclaimer- some places don't do Daylight Savings, and even those that do differ by country on exactly when it occurs. So it's still not always right. But I still think it's cool.
Laser cutting done at TechShop