Probably many of you already know Care2. I just discovered it and thought it could be a good resource to share.
It’s a Portal/Community/Social Network dedicated to green living, health, human rights and protecting the environment
"The premise of Care2 is simple: One person can make a difference.
Over 7 (8 actually) million wonderful people discover, share and take action on Care2 and Care2's The Petition Site. It's the largest online community of people passionate about making a difference"