Here's The Green Skeptic's list of the top ten green books of the decade 2000-2009. This reflects my personal favorites and not necessarily their influence or popularity among the reading public.
1.) The World Is Flat 3.0: A Brief History of the Twenty-first Century by Thomas L. Friedman
2.) Ill Nature: Rants and Reflections on Humanity and Other Animals by Joy Williams
3.) Break Through: Why We Can't Leave Saving the Planet to Environmentalists by Ted Nordhaus and Michael Shellenberger
4.) Wanderlust: A History of Walking by Rebecca Solnit
5.) The Song of the Earth by Jonathan Bate
6.) Red Sky at Morning: America and the Crisis of the Global Environment by James Gustave Speth
7.) The White Man's Burden: Why the West's Efforts to Aid the Rest Have Done So Much Ill and So Little Good by William Easterly
8.) Worldchanging: A User's Guide for the 21st Century by Alex Steffen
9.) A New Theory for American Poetry: Democracy, the Environment, and the Future of Imagination by Angus Fletcher
10.) Eye of the Albatross: Views of the Endangered Sea by Carl Safina
What were YOUR favorite "green" books of the decade?