Also remember that refractions in a perfect sphere are rotated 180°

Here's a Layer Style tutorial i found that turns whatever you're painting into a water drop blending style which could be good for making a water drop brush and modifying the Jitter settings within the brush panel under shape dynamics and scattering to create many drops or maybe condensation.
http://www.n-sane.net/effects/water-drops/index.php

This along with what I was mentioning before could create a different path all together. I thought it was kinda neat.