I'm an Independent Voter - Can I Vote in the Primary in Massachusetts?

Yes you can! From FairVote:  Registered Democrats and Republicans can only vote for their own party in the primary but independent voters may decide which party they would like to vote for. (Also see IndependentVoting.org)

• Bump, Glodis produce some bruises (By Shaun Sutner Worcester TELEGRAM & GAZETTE STAFF) Democrats lost ground, dropping from 31 percent in 2006 to 30 percent this year, while Republicans saw their ranks reduced even more markedly, shrinking from 13.9 percent four years ago to 12.8 percent today. As it stands, independents continue by far outnumbering Democrats and Republicans combined in Worcester County. 
• Dogfight in 10th - District features tough primary races as GOP aims for control of House (By Brian C. Mooney, Boston Globe Staff)
• Clerks predict 20 percent voter turnout in Massachusetts primary (Dan Ring, The Republican) Top election leaders in Western Massachusetts are predicting a low voter turnout for Tuesday’s statewide primary, citing the lack of a governor’s contest, long-standing apathy about preliminary elections and a growing number of independent voters.