This list is the opinion of the creators of the www.care2.com site.
If you have additions or comments about this list, feel free to post them below!
Conservation International (www.conservation.org)
Defenders of Wildlife (www.defenders.org)
Earthwatch Institute (www.earthwatch.org)
Friends of the Earth International (www.foei.org)
National Parks Conservation Association (www.npca.org)
The complete list can be found here