The PolitiFact website is owned and operated by the Tampa Bay Times. It publishes the Truth-O-Meter rating system, in which a true statement is identified as True and a bold, complete lie is rated Pants on Fire (from the taunt "Liar, liar, pants on fire"). The system allows for degrees of truth in between. Political commentators across the entire ideological spectrum have disputed PolitiFact's evaluations, but the website's judgments are widely quoted. The site has been active since August 2007.

politifact.com

FactCheck.org is a project of the Annenberg Public Policy Center at the University of Pennsylvania. It's billed as a nonpartisan, nonprofit organization that verifies or debunks statements by and about politicians in speeches, ads, press releases, debates, interviews, and mass e-mailings. The organization publishes its findings on its website and also distributes material via podcast. FactCheck.org discloses its own funding sources on its site. Its archives go back to 2003.

factcheck.org

The Fact Checker is a widely read column and blog by respected Washington Post reporter Glenn Kessler. He rates the veracity of political statements in a five-level range. (Kessler assigns four Pinocchios for whoppers and a Gepetto to those rare statements that are completely true.) Although his assessments have been criticized by partisans from both left and right, he's generally considered an evenhanded evaluator. The Fact Checker website archives go back to September 2007.

washingtonpost.com/blogs/fact-checker