When I was looking for a house several years ago, I had a pushy buyer's agent whose game was to try and put me in a house at or just barely above my maximum price. All she was trying to do was maximize her commission, which was not cool by me -- I was trying to find a place to live on a budget and she wasn't listening to my needs in a house. If I use a realtor again I'll try to find a buyer's agent who will work for a fixed fee. Damn those realtors.
Anyhow, you know about the registry of deeds, right?
http://www.hampshiredeeds.com/
If you have the street address of the property it will tell you some good information:
- when the house was built
- what the house's last sale price was
and some other stuff that I forget about now.

Also there's a website listing US assessor's offices at:
http://indorgs.virginia.edu/portico/assessors.html

It can be good to know what the last sale price of the home was.