Project Vote Smart is a nonpartisan, nonprofit political information system founded by former presidents Ford and Carter. It includes voting returns, candidate information, campaign finance records, and so on.
http://www.vote-smart.org

California Voter Foundation is a nonprofit, nonpartisan organization dedicated to applying new technologies to provide the public with access to the information needed to participate in public life in a meaningful way.
http://www.webcom.com/cvf

Corporate Watch pursues corporate accountability, human rights, social and environmental justice. The site contains information about corporate abuses and efforts to curtail the activities and power of organizations like the World Bank and the International Monetary Fund.
http://www.corpwatch.org

The Initiative &Referendum Institute provides nonpartisan and nonpolitical information about the initiative and referendum process at all levels of government. Its sister site, BallotWatch.org, provides state-by-state summaries of initiatives and referenda on the ballot.
http://www.iandrinstitute.org