Folks, I'd like to recommend a new Topic under the Using Arduino Section of the Arduino Fórums.
Energy Supply and Conservation. This could cover every thing from Solar and Battery Technology, as well as Energy Conservation methods for your Microcontrollers and Shields. We could cover Sleep methods, Wake Methods, etc... Disabling/Enabling functionality when unneeded, etc...
This topic needs specific focus, especially as we begin to network our Arduinos to the outside world or place them in remote locations. We can't be running wall warts everywhere, nor constantly changing batteries. All of us need to borrow ideas from one another specific to supplying and conserving energy. Hardware and Software ideas alike can be shared.
I would put it right between General Electronics and Microcontrollers.