These guys from Stanford did some surface tension research with water and polyethylene glycol (PG). Watch the video. My favorite is when they use sharpies to make a hydrophobic barrier and sort different coloured (with different concentrations of PG) to sort the droplets. The video show specifically how the water and PG droplets interact with each other and surrounding vapour on a glass surface. Chasing, sorting and other events take place in this awesome soundtracked video.