Like a nagging parent you can stash away in your pocket, Japan's Design Factory teamed up with the country's national weather service to create this compact UV meter/skin checker that lets you know when it's time to get out of the sun.
Determining the intensity of the sun's ultraviolet rays is as simple as holding the Beauty Sign Plus up so it gets a direct blast of light, while keeping tabs on your skin so you can stay one step ahead of dehydration requires you to press two metal contacts to your skin so it can measure the electrical impedance between the two. The less moisture there is in your skin, the less juice flows. It's easy to use, and for just $30 consider it insurance against sun burns, heat stroke, and other long term devastating effects of the sun. [Japan Weather Association via Akihabara News]