Earth Day is this Saturday. If you haven't made plans yet, check out the Earth Day Network site and see if there are any events in your area. Check out your Ecological Footprint while you're there (oh, dear, I thought I was doing well, but if everyone lived like me, we'd need 4.4 Earths to support everyone). If there aren't any events in your area and you think there ought to be, the Network provides an Earth Day in a Box, a set of resources that can help anyone become a community leader and organize a fabulous Earth Day.
Me, I'll most likely be on my knees in the dirt, pulling weeds and perhaps putting some of my home-grown seedlings in the ground. They're outside right now, the little darlings, in the shelter of a rickety old mini-greenhouse, its old, rotted plastic cover now replaced with a swath of perforted plastic.