I would agree with Melanie, I think if you are looking for a roomate situation, Craigslist is a good start.
Might I also suggest, if you have contacts in the Boston area, that you let everyone you know aware of what you are looking for. Facebook can be a great way to get the word out. You never know when someone 'knows someone who knows someone' so to speak. Always better to have some sort of connection. Also, friendly safety reminder to do background checks on any potential roomate.