Thanks folks!
You can do these with a fancy trigger device but I just use the poor man's method (sheer numbers). They're actually easy to do.
I wish I had a photo of the setup (pictures are worth a thousand...) but for now a description will have to do.
You will need: a wide shallow baking dish, reflection panel (any piece of white cardboard), a zip-lock baggie (to hold the water), a tripod, a remote shutter/clicker, and most importantly an
external flash (and way to trigger it from the camera).
Note that an on-board flash will not work. You want to catch spectral highlights on the water drops. These are best created at angles (rather than face-on).
1) Position the reflection panel, external flash, and camera (on the tripod) in a rough triangle around the baking dish. The panel and flash can be fairly close to the dish. You can play with positioning for different spectral effects.
2) Position your zip-lock baggie (full of water) at least 12" over the baking dish and poke enough of a hole in the bag to allow a fairly consistent drip.
3) Set your camera to "manual focus". Hold a pencil (or other object) in the water at the precise point of the drops and focus on this point.
4) Shoot (be sure to use the remote shutter/clicker).
5) Repeat step 4.
This is a numbers game. With enough shooting you'll usually end up with quite a few good shots. Although I do have to admit that these somehow lose their magic after a couple of hundred shots.
I like to set a low-value white balance to give the shots a blue tint (they're actually dull grey right out of the camera). For other effects you can use different colored reflection panels.
Enjoy!
The Egg