FactCheck.org.
From the Annenberg Public Policy Center at the University of Pennsylvania, this nonpartisan, nonprofit, consumer advocate site aims to monitor the factual accuracy of what is said by major U.S. politicians.

PolitiFact.
This Pulitzer Prize winning site was started by the St. Petersburg Times as a place where, “Reporters and editors from the Times fact-check statements by members of Congress, the White House, lobbyists and interest groups and rate them on our Truth-O-Meter.” ABC’s Sunday morning political show This Week, is also joining PolitiFact to check up on the lawmakers they interview.