heard a story on npr's day to day about making little changes to help the environment. and it was actually something i'd been doing for years :: changing the margins on word processing documents to save paper.
changethemargins.com is a campaign to get people and companies to change the margins on documents; you can sign the petition to encourage microsoft to change the default margin from 1.25 inches to 0.75 inches. (i usually print half-inch margins, and am even known to go down to 0.12 inches on draft copies that are just for me.) a research team at penn state did a study showing the incredible savings in money, paper, and energy when this small change was instituted.
so, even if you don't sign the petition or get involved in this movement, at the very least, go to your ms word default settings and change the margins. you can save a tree. you might even save the planet.