I searched around on there, went down to Contact us, then Common Questions and this is what I found:
[I][B] Is The Rainforest Site a nonprofit organization? [/B]
The Rainforest Site is [I]not[/I] a nonprofit organization and cannot accept financial donations directly. [/I]
[I] GreaterGood.org is the nonprofit foundation arm of The Rainforest Site and the GreaterGood Network. GreaterGood.org has applied for and is awaiting its 501©(3) status. When granted, that status will be retroactive to March 21, 2006.
[I][B] How Do I Know This is Real? [/B]
There are a number of ways you can be assured that The Rainforest Site is for real. [/I]
[I] Read the article on our suite of click-to-give sites, including The Rainforest Site, at Wikipedia.
Then they list 4 groups for you to contact (physical address, phone, email and web addresses) directly to make sure the group is legit: The Nature Conservancy, Rainforest Conservation Fund, World Land Trust - US, Friends of Calakmul.
They give all the contact info of these groups if you want to confirm this is a honest site.