Sometimes it's the accidental discoveries that make the biggest impact. Researchers at Pacific Northwest National Laboratory have learned that carbon-rich nanorods created in a botched experiment might be ideal for harvesting water. When there's relatively low humidity (below 50 percent), the rods trap water inside their gaps; if it's any more humid, however, they promptly expel that water as vapor. It's a very unusual trait that's likely caused by water condensing into a "bridge" in the nanorods, whose surface tension forces them to close and eventually kick the water out.
If scientists can refine the shape of these nanorods and get them to spray water on a consistent basis (only 10 to 20 percent do that right now), the implications are huge. They'd be ideal for harvesting and purifying water in dry climates -- you could gather ambient moisture until there's enough to drink. Alternately, you could use it for anti-sweat clothing that soaks up your perspiration and spits it outside. All told, you'd have direct control over just when and how you get water.