Heritage Preservation Association (HPA)
http://www.hpa.org/

National Trust for Historic Preservation
http://www.nationaltrust.org/

National Center for Preservation Technology and Training
http://www.ncptt.nps.gov/
promotes the preservation of prehistoric and historic resources through its research, technology, training, and grants programs

Heritage Conservation and Historic Preservation
http://home.vicnet.net.au/~conserv/hp-hc.htm
This site, from the Preservation and Storage Division of the State Library of Victoria,  offers a range of resources for anyone interested in the care of heritage material, sites and structures.

National Trust Library of the University of Maryland http://www.lib.umd.edu/NTL/ntl.html

Preservation Alliance of Minnesota
http://www.tc.umn.edu/~brook024/pam.htm

Conservation OnLine: WWW
http://palimpsest.stanford.edu/

International Council on Monuments and Sites (ICOMOS)
http://www.icomos.org/

National Park Service
http://www.nps.gov/

Canadian: CultureNet
http://www.ffa.ucalgary.ca/