Campus Ecology (National Wildlife Federation)
EcoLex: the Gateway to Environmental Law. (Sponsored by the UN Food and Agriculture Organization & the Int'l Union for the Conservation of Nature)
Ecological Society of America (Scientific, non-profit organization founded in 1915)
International Society for Environmental Ethics. (Born out of the American Philosophical Association. Site has extensive bibliography and Society newsletters)
International Union for the Conservation of Nature. (Oldest and largest global environmental network)
National Council for Science and the Environment (Non-profit organization with heavy participation by academic and professional scientific societies)
World Resources Institute. (Environmental think tank) Many downloadable documents.
World Water Council. (Non-profit based in France). Council reports and initiatives around the world.