A while back, while googling around, I found this thermostat controlled waterproof baby pig heating pad that seems good for placing under trays to keep solutions from cooling off; http://www.apug.org/forums/forum43/35600-sue-weeee.html
Today I found this Water Timer; http://www.leevalley.com/garden/page...280,33160&ap=1
They (Nelson) also make a model that runs for 5 minutes, then stops for 10 minutes for up to 3 hours; http://www.lrnelson.com/products/model.cfm?MODEL=226
The first water timer would be great for those times you can't get back to the darkroom to shut the water off, and the second one would be like an automated dump and soak wash. Don't know which one I'll be getting just yet, but both would save in hot water bills.
Have you discovered any equipment not meant for darkroom use that's now indispensable in your darkroom?