NeverWet is a truly amazing "superhydrophobic" coating that, once applied, completely repels water. Developed by Ross Nanotechnology, the coating's applications seem endless: It makes things super-easy to clean; it completely prevents rust, as water never actually comes into contact with the surface of the material; it prevents ice from sticking to things like power lines or airplane wings; it even reduces friction of water flowing through pipes coated with the stuff, meaning less energy would be needed to pump that water. Check it out:

Back when I had a car, I used to use a similar product called Rain-X on the windshields. What was a pain was that you had to reapply the stuff every few weeks or even days depending on how much it rained. Durability is one of the NeverWet team's goals, and to that end they've achieved success with a trial using a piece of metal submerged in seawater for a year.