Harvard University has a new Google custom search for 590 think tanks and research centers, allowing users to more easily check policy proposals of hundreds of think tanks in mere seconds.
Here is how Harvard defines a "think tank" for the search:
For the purposes of this search, think tanks are defined as institutions affiliated with universities, governments, advocacy groups, foundations, non-governmental organizations, and businesses that generate public policy research, analysis, and activity. Inclusion is based upon the relevancy of subject area to HKS coursework and scholarship, the availability of the think tank’s research in full-text on the website, and the think tank’s reputation and influence upon policy making. The list represents a mixture of partisan and non-partisan think tanks.
Think Tank Search