Guidestar - the world's largest source of information on nonprofit organizations where you can sign up for a basic account free in just a minute or two and begin reading Form 990 for non-profits and possibly get a glimpse of where they are getting their money. When you read a 990, you might not see everything but sometimes they can be quite interesting.
Sign up, write down your user name and password and bookmark the site. Then simply search for the non-profit group you are interested in at: https://www.guidestar.org/Home.aspx
Plug in the name of the organization you are looking for:
(You can also search with other keywords such as ENVIRONMENTAL or MAINE.)
Find the organization you want and click on its name.
Off to the right, click on "Show Form 990"
Select the year you want
More information: http://www.windtaskforce.org/page/investigate-them
Currently, Maine law does not require non-profits to disclose the names of its donors. Considering that some non-profit groups lobby so intensively that they impact legislation more than individual legislators, it would be nice if the public could see who is handing over the large money.
The Foundation Center
Another valuable source of info is the Foundation Center. See: