Researchers at Purdue University have developed a special metal alloy that can spontaneously split saltwater into hydrogen and oxygen, generating both hydrogen fuel and clean fresh water at the same time.
The metal alloy is mostly aluminum, with some gallium, indium and tin thrown in for good measure. When submerged in water, the alloy causes a spontaneous reaction that boils the water to generate steam while also splitting off hydrogen gas. The steam can the be condensed into sterilized drinking water, while the hydrogen goes into a fuel cell to generate electricity. This process will continue until the aluminum is all used up, leaving non-toxic aluminum hydroxide waste behind, which you can either put in a landfill or eat if you have an ulcer.
This reaction doesn't need purified water to work. It'll do just fine with dirty water, or even salt water, which opens up all kinds of possibilities. Primarily, the researchers are looking to develop a small (sub 100 pound), inexpensive, entirely self-contained water purifier and power generator that could be air-dropped into remote villages in Africa. The overall cost for the system works out to be about $1 per gallon of fresh water and $0.35 per kilowatt of electricity, which is pretty cheap considering that no infrastructure is required besides the reactor itself.
Eventually, we might start seeing this technology show up in boats, submarines, robotic underwater vehicles, or (and this is just my hope) a little portable gadget you can take camping with you.