Designers Alberto Medo and Francisco Gomez Paz have developed solar powered purification bottles, cleverly named Solar Bottles. They hold over a gallon of water, and take about six hours to kill off the majority of things that aren't good for you, through a combination of high temperature and UV-A exposure. I think these things are a great idea. Because, let's face it, drinking a camping buddy's urine makes you less of a survivalist, and more of a sicko fetish person.
Solar Powered Water Purification [engadget]