With gas prices climbing, how about optimizing traffic flow through the city? It makes no sense to me that anywhere I go in (greater) Philadelphia I get to stop at every 2nd light. Whether I accelerate to 20, 30, or 40 mph, it's NEVER a decent stretch of green, anywhere. I happen to be visiting other cities, and miraculously they are able to prioritize, and synchronize traffic patterns.
I imagine something like this would help cutting down on pollution, significantly (and increase my mileage, too)