Deeds & Records:
Suffolk County:  http://www.masslandrecords.com/malr/ma025/index.htm
Essex County:  http://www.salemdeeds.com/goget.asp

GIS Pages:
Marblehead: http://gis.marblehead.org/webgis/
Manchester: http://host.appgeo.com/manchesterma/
Wenham: http://www.wenhamma.gov/gis/gis_frame.htm

Assessment resources:
Marblehead: http://marblehead.patriotproperties.com/default.asp
Manchester: http://manchester.patriotproperties.com/default.asp
Wenham: http://www.wenhamma.gov/depts_forms&docs/assessors/fy07values.pdf (2007 PDF)
Hamilton: http://data.visionappraisal.com/HamiltonMA/search.asp
Beverly: http://beverly.patriotproperties.com/default.asp
Boston:  http://www.cityofboston.gov/assessing/search/

Hamilton Zoning Map:  http://www.hamiltonma.gov/Pages/HamiltonMA_Planning/zoning2009%20map.pdf
Hamilton Zoning Bylaws: http://www.hamiltonma.gov/Pages/HamiltonMA_Planning/ZoningBy-laws2010forwebsite.pdf
Marblehead Zoning: http://www.ecode360.com/?custId=MA1991

Town Demographics:
http://www.city-data.com/city/Massachusetts.html

Real Estate: 
www.nemoves.com
http://www.realtor.com/
http://www.fountainsland.com/properties.aspx

Maps:
http://maps.google.com/