Anyone who has spilled a glass of water knows droplets have minds of their own. There is no telling where they will splatter. But droplets, beware! Tom Krupenkin may have your number. Angling to become the Neptune of Nanotech, the Bell Labs physicist says he has learned to make these slippery characters do his bidding. Using tricks of the computer chip-making trade, Krupenkin thinks he can drive teensy drips and drops to perform all sorts of useful feats, from cooling microchips to streamlining torpedoes.