A Union of Concerned Scientists slideshow exposes the absurdities of electrical utilities' reliance on coal.
I found these two slides to be particularly galling:
There's also a quiz about coal and renewable energy options, particularly in the Southeast, and a useful Take Action page that helps guide you through a phone call to your utility to demand clean, renewable energy sources.
For another great look "behind the light switch," check out iLoveMountains.org's tool for finding your connection to mountaintop removal. Just plug in your zip code and see where your power is coming from.