AMIGOS Library Services, In. - Imaging & Preservation Services - AMIGOS is an excellent resource for basic preservation information, training, site surveys, disaster planning/response and digital imaging. They have developed excellent tools on their website, including lists of imaging and preservation resources and a variety of pamphlets on preservation topics.
Conservation Center for ARt and Historic Artifacts (CCAHA) - CCAHA is a regional conservation center in Philadelphia, PA. They sponsored the Architectural Records Conference and the Architectural Records Symposium. They have also published the proceedings on the Web.
Northeast Document Conservation Center - NEDCC is a "nonprofit, regional conservation center [...] Its mission is to improve the preservation programs of libraries, archives, museums, and other historical and cultural organizations." Their main services include collections treatment, consultation and education through publications and outreach programs. NEDCC has useful tools and publications available for viewing and purchase.
Regional Alliance for Preservation (RAP) - RAP is a membership network for Preservation Field Service programs and Regional Conservation Centers (ARCC). "The mission [...] is to provide comprehensive preservation information to cultural institutions and the public throughout the United States." RAP does not provide direct service, but their website can direct you to local regional members.