The Watercone is one of those brilliant "Why didn't anyone think of that before" devices. You fill it with salt water and wait while the heat from the sun causes the water to evaporate, catching it in a gutter on the side - distilling the water. When it's done, you flip it over and open the bottle top to release the water. A simple, low-cost way to distill fresh water from salt water.
via The Seitch Blog