I was working in a company on Monday who make a very innovative set of products. Based upon Nano technology. They make a coating which is hydrophobic. It will prevent corrosion on bare metal, can be pained over paint, a version for wood and a version for stone. Amazing stuff.
The applications are of course extensive. Marine usage would be huge as would painting of brick and blocks on housing. If the water cannot soak in then it will not absorb heat as it evaporates and dries.