Grey literature is an important source of information.

Grey literature is defined as "information produced on all levels of government, academics, business and industry in electronic and print formats not controlled by commercial publishing" ie. where publishing is not the primary activity of the producing body." —ICGL Luxembourg definition, 1997. Expanded in New York, 2004

Resources

•     Grey Literature: Introduction
•     GreyNet International Directory of organizations in grey literature from GreyNet International
•     Grey Matters 

Policy Reports and Working Papers

• Brookings Institute
• Canadian Health Research Collection
• Conference Board of Canada e-Library  In addtion to the e-Library, look to particular Centres for research on specific topics.  Go to Conference Board of Canada and scroll down to the bottom of the page.  Select Sitemap. Under Special Projects you will see  Centre for the North, Centre for Food in Canada, How Canada Performs, etc.
• NBER Working Paper Series
• Policy File Index
• Social Research and Demonstraton Corporation A non-profit research organization, created specifically to develop, field test, and rigorously evaluate new programs.

Think Tanks page contains links to think tanks, university research centres and other public interest groups.