The GLOBE Program is asking people around the world to participate in a project to map light pollution from February 25 through March 8. All you have to do is go outdoors after dark -- you can go right outside your house or report from any location you choose -- and look up at Orion. Then you visit the GLOBE website's reporting form and click a button next to the sky chart that looks like Orion from your location. I've gone outside both Monday and Tuesday and it looks like I can see down to just a little fainter than magnitude 4 from my street, which has bright streetlights every 100 feet or so. The page encourages you to take observations on multiple nights, reporting even if it's cloudy, and also to try multiple observations on one night from locations separated by at least a kilometer.
Why do this? More and more of humanity is living in cities with severe light pollution, which means that they know less and less about the sky -- and, perhaps, have less awareness of Earth as a planet. Many people have never seen the Milky Way, and don't realize that light pollution is not only an ecological issue (it can play havoc with such things as bird migration and the habits of nocturnal animals), it's an economic one. Much of light pollution represents wasted light, from fixtures that send as much light up into the sky as down onto the ground.
Anyway, please help out the GLOBE program by reporting the level of light pollution in your area sometime before March 8!
Thanks to Phil Plait for the tip.