This site is chuck full of free data layers for Massachusetts. It has Tiger Street Index, Census Data, Black and White Orthos, Color Orthos, Building Footprints, Congressional , Senate, House voting districts, Schools, etc. for the state of Massauchusetts. All freely downloadable or on CD for a nominal fee.
NOTE: The Massachusetts Assessors' Parcels layer for most Massachusetts Towns was released recently and can be downloaded from here. Sadly Boston is still at Level 0 in terms of the quality and quantity of information you can get from this feed.