Additional Resources and Links

DIY Photography has a very good article by Corrie White called The Comprehensive Water Drop Photography Guide. Corrie is one of the leading drop photographers.
Wayne Fulton’s scantips website has some very good information on valves, nozzles and drops.
Tobias Braeuning has a good article about his set up.
Kevin Lewis’s PhotosbyKev website has a another good guide (read the comments) called Water Droplet Photography.
strobist: How to Photograph Water Drops with One Speedlight
Video Tutorial by Daniel Nimmervoll (in German) Wassertropfen Highspeed Fotografie Folge 1
Advanced 3 valve Setup by Daniel Nimmervoll (in German) Mein Aufbau für Wassertropfen Fotos

Drop Art Photography Facebook group. Group dedicated to water drop photography (not my group).

 

Other DIY Devices

Ramigrafx has another Arduino based water drop controller with full build instructions.
Photoduino. A multi function camera trigger.
Michael Ross has a comprehensive guide for building a High Speed Photo Trigger based on the Arduino Mega

As well as selling kits, HiViz have good information on trigger circuits (sound, delay, photogate, etc) in the tools section. Also check out the assembly instruction section.

 

Commercial Devices

Here are some of the commercial products you can buy. Most of these are expensive which is why I built my own.
HiViz AstroSplash Drop Controller
MJKZZ water drop photography controller
Camera Axe
The Drip Kit
Splash Art Kit
Stopshot
The Time Machine

 

DIY Shutter Release Cables

http://www.doc-diy.net/photo/remote_pinout/