GreenAnswers is a Yahoo! Answers that specializes in environmental issues. As a social question and answer site, anybody can ask a question and then anybody can answer it. With a community specializing in Green topics, you’ll be able to find knowledgeable, authoritative sources for whatever you’re looking into while giving back to the community with your knowledge.
I found out about GreenAnswers when I was looking into the best way to dispose of shingles. I found my answer and more with GreenAnswers. If Green interests you, the site itself is worth visiting regularly. They also have an Environmental News feed and regular blog posts that are quite educational.
Beyond just the times when you have Green questions of your own, you might find some motivation to participate in the site because of their tree planting campaign. Join GreenAnswers.com and they will plant a tree and for every 5 questions that you answer after that. Seems like a win-win!