First, the setup:
Ziploc bag partially filled with water and Scotch taped to the cabinetry above the sink.
Nikon D300s and Sigma 70-200 f/2.8 with Phottix wireless remote shutter release and SB-400 on an SC-17 cable. Aperture set to f/11, shutter at 1/320th, manual focus.
Next, making the drops:
Used a razor blade to put a very small slice in the bag to create a constant, yet slow drip.