I tried some water drop shots in my sink and was fairly happy with the results that I got. All I used for lighting was my 430EX mounted on camera. I tried out some different settings and had a plate on the bottom of the sink. I also did some shots with the plate mounted up so that it was higher.
I also played around with some of the shots in Photoshop and applied some filters to create some more colorful and interesting perspectives on the water. For the shot above, I applied a glow filter that gave it a highlight look to the black and white plate. Most of my shots were shot at an exposure of 1/250 and I was surprised that the results were as good as they were. I would have thought that I needed a faster exposure to get a sharper image of the drop. The camera settings were around ISO 100-200, aperture at f/5-5.6. For focusing, I usually have it autofocus on the area first, and then switch it to manual focus.