Charlotte van der Waals Clocks

This is new spin on a old classic. Instead of fiddling with a bunch of buttons to find out the time in another distant city, or worse, perform some dreaded mental arithmetic, why not just purchase one of these? The clocks have

12 slides, each with the name of two major cities; together, the 24 cities represent the 24 global time zones; to find the local hour in another time zone, simply roll the clock so that the city representing that time zone is on top.

Genius I say.

And you get it here.