Elections Information, from the Secretary of the Commonwealth of Massachusetts, including Voter Registration, Where Do I Vote, Candidates and Ballot Questions ...
Voting and Election Information from the Massachusetts League of Women Voters.
Elections and candidate information from Project Vote Smart.
Massachusetts Office of Campaign & Political Finance, including campaign finance activity for all statewide candidates.
Open States, from the Sunlight Foundation, includes information on legislators, including campaign finance and voting records.
PolitiFact.com, a project of the Tampa Bay Times, includes the "Truth-O-Meter," which fact-checks political statements, and rates claims for accuracy.