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. 
Boston Dance Alliance
A comprehensive resource for the Boston dance community, including The Greater Boston Dance Directory which includes listings for dance instruction, rehearsal and performance facilities and press and grant information. It is produced once a year as a book and is also available to download off the website.
http://www.bostondancealliance.org/

ArtistLink's Arts Space Finder
Artistlink is a new initiative which helps artists, developers and municipalities in the creation and preservation of affordable artist space. ArtistLink's Arts Space Finder is a web tool designed to help you find or list space to create in Massachusetts and the Boston Metro area.
http://www.artistlink.org/?q=artspacefinder
Cambridge Arts Council
The Cambridge Arts Council has listings of Rehearsal, Performance, Meeting and Classroom spaces available in Cambridge.
http://www.cambridgeartscouncil.org/resources_listings.html
Matchbook.org
MatchBook.org is a free performing arts marketplace designed to make connections between New England's performing artists, presenters and communities. The site's foundation is an easy-to-search directory of the region's performance venues, artists and organizations that book performances. MatchBook.org helps MATCH New England's performing artists with the theaters, community centers, libraries, schools, galleries, clubs and coffeehouses that hire - or BOOK - them to perform.
www.matchbook.org