Want to stop Global Warming? Just follow 14 simple rules

Steve Souders, author of the YSlow 14 rules for high performance websites did some back of the envelope calculations on the carbon footprint impact of not adhering to some of the rules.

High Performance Web Sites :: How green is your web page?

It's kind of fun to think how much impact some little http headers can have on the world.  By my calculations, I've saved about four rainforests in the last year :-)