Multitudes of websites deal with historic preservation. All can be found with any search engine. The following are some less well known sites that support preservation.

Friends of 1800 Market (San Francisco)
San Francisco Architectural Heritage
San Francisco Heritage Primer
Preservation Action Council of San Jose
Berkeley Architectural Heritage Association
Oakland Heritage Alliance
San Francisco Preservation Consortium
(To inquire about joining, send e-mail to: Cynthia.Servetnick@gmail.com)
Los Angeles Conservancy
Save Our Heritage Association (San Diego)
Pasadena Heritage
The Recent Past Preservation Network
City and County of San Francisco, Planning Department
City of Oakland, Community & Economic Development Agency, Planning and Zoning Division
City of San Jose, Planning Division

Fun and Educational Stuff
San Francisco Fire Department Museum
The Fire Museum Network
The Virtual Museum of San Francisco
San Francisco Museum & Historical Society
Environmental Design Archives, University of California, Berkeley
Bancroft Library, University of California, Berkeley
Nolli Map of Rome
Ben Pease, Pease Press
David Rumsey Map Collection
American Memory, Library of Congress
Public Architecture and 1% Solution
Vernacular Language North
National Park Service, Recent Past Initiative
National Register of Historic Places, Travel Itinerary