"FactCheck.org is a project of the Annenberg Public Policy Center of the University of Pennsylvania....a nonpartisan, nonprofit “consumer advocate” for voters that aims to reduce the level of deception and confusion in U.S. politics. We monitor the factual accuracy of what is said by major U.S. political players in the form of TV ads, debates, speeches, interviews and news releases."
"Headquartered at the Annenberg Public Policy Center of the University of Pennsylvania, FlackCheck.org is the political literacy companion site to the award-winning FactCheck.org. The site provides resources designed to help viewers recognize flaws in arguments in general and political ads in particular."
Pulitzer Prize wining site run by editors and reporters from the Tampa Bay Times (Florida) newspaper. "PolitiFact is a fact-checking website that rates the accuracy of claims by elected officials and others who speak up in American politics.... The PolitiFact state sites are run by news organizations that have partnered with the Times." Read about their principles under 'About Us.'