One of the "hottest" applications of what I am doing at The University of Edinburgh as a part of my PhD is the "coalescence induced jumping of droplets for cooling purposes over specially treated surfaces". By "specially treated surfaces", I mean super-hydrophobic surfaces upon which droplets (mainly water) sit like a ball sits on a floor.
When two such neighboring droplets coalesce, the final droplet will have a smaller surface area than the combined areas of the first two. This reduction in the area supplies some energy for the final droplet to jump off the surface. That's the physics (certainly not all!) behind it.
I know what the applications of this interesting phenomena are, but it's really difficult to explain them just using words to friends, parents etc. That's when I found this video made by a research team from Duke University.