These resources are excellent sources of information on performance, rehearsal, and workspace in the region whether you are searching in Boston, in other parts of Massachusetts or even in other parts of New England.
SpaceFinder Mass is a free service for theatre artists to discover viable performance and rehearsal space based on location, price, amenities and up-to-date availability. Built by national non-profit Fractured Atlas, SpaceFinder currently serves 12 cultural hubs across North America (NYC, LA, Bay Area, Chicago, DC, Philly, Toronto, etc.) and has been dubbed by TheNextWeb as the 'Open Table' for artists.
Cambridge Arts Council
The Cambridge Arts Council has listings of Rehearsal, Performance, Meeting and Classroom spaces available in Cambridge.