The Boiler solar-powered watch by Freestyle uses a battery charged up from sunshine. It comes with both a power indicator and a power saving function, though the chances you'll need to use them are slim – according to Freestyle, it receives 12 months of power on a single charge. So basically, the only way your watch will ever run out of juice is if you live in a cave all year long.

The Boiler has a chronograph, alarm, timer, dual time and a backlight display for darker areas. Price for solar coolness: $115. [Treehugger]