As a huge fan of FlowingData, NPR and electricity, I'm super excited about this interactive map that gives you a clear view of the structure of the U.S. power grid. Clicking through, you'll see how areas of the country currently are (and aren't) connected to one another, what's in the works to improve the system, and why that matters (a lot) when you start talking about alternative energy sources. Good stuff.
In this picture, you can see the yellow lines that really seem to do a good job of efficiently linking up the whole country. Those power lines haven't been built yet. In the interactive part, you can take those off, revealing a clearer view of our current transmission infrastructure that looks more like a series of occasionally connected river systems than a grid.