You're likely familiar with commercials and debates about the inefficiency of the current U.S. electric grid. It's been part of a larger discussion about energy conservation and greener methods of energy production. The idea some have had is that the U.S. wouldn't need to produce so much electricity if less power were lost in the power grid.
NPR has tracked this debate in its series "Power Hungry: Reinventing the U.S. Electric Grid." One feature in this coverage has been the "Visualizing the U.S. Electric Grid" series of maps.
These maps feature numerous layers that can be turned on and off and which depict such information as current and proposed major power lines, which states depend more on which sources of power, where power plants using different power sources can be found, solar power potential, wind power potential, etc.