Ballotpedia: The digital encyclopedia of American politics and elections. Their goal is to inform people about politics by providing accurate and objective information about politics at all levels of government.
FactCheck.org: A nonpartisan, nonprofit “consumer advocate” for voters that aims to reduce the level of deception and confusion in U.S. politics. They 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. Their goal is to apply the best practices of both journalism and scholarship and to increase public knowledge and understanding.
OpenSecrets.org: The nation's premier research group tracking money in U.S. politics and its effect on elections and public policy. Maintained by the Center for Responsive Politics, a non-partisan, independent, non-profit organization.
Project Vote Smart: A non-partisan, non-profit educational organization funded exclusively through individual contributions and philanthropic foundations.
PolitiFact: A project of the Tampa Bay Times and its partners to help find the truth in politics.
Smart Voter: One of the most comprehensive and reliable sources of unbiased information for voters on the Web. The service is made available to the public through partnerships with the League of Women Voters and election officials of various states and local communities around the U.S.