The following list is by no means complete, but provides some of the more prominent collections that are models for Houston ARCH in one way or another.  A more comprehensive listing of LGBT historical societies and organizations is available at:

http://www.fordham.edu/halsall/pwh/index.html

ACT-UP Oral History Project (New York, NY; San Francisco, CA)

http://www.actuporalhistory.org/

Boston History Project (Boston, MA)

http://www.historyproject.org/

Chicago Gay History (Chicago, IL)

http://www.chicagogayhistory.com/

The Gerber/Hart Library (Chicago, IL)

http://www.gerberhart.org/

GLBT Historical Society (San Francisco, CA)

http://www.glbthistory.org/

HAPPY Foundation (San Antonio, TX)

http://www.sacurrent.com/columns/story.asp?id=69586

Homosexual Information Center (Oviatt Library, California State University, Northridge)

http://library.csun.edu/Collections/SCA/SC/fdgds3g

Jean-Nickolaus Tretter Collection in Gay, Lesbian, Bisexual and Transgender Studies

(Elmer L. Andersen Library, University of Minnesota, Minneapolis)

http://special.lib.umn.edu/rare/tretter.phtml

The Legacy Project (Chicago, IL)

http://www.legacyprojectchicago.org/

Lesbian Herstory Archive (New York, NY)

http://www.lesbianherstoryarchives.org/

ONE Archives (Los Angeles, CA)

http://www.onearchives.org/

OutHistory.org (New York, NY; virtual collection)

http://outhistory.org/wiki/Main_Page

National Archive of Lesbian, Gay, Bisexual, and Transgender History (New York, NY)

http://www.gaycenter.org/community/archive

New York Public Library (New York, NY)

http://legacy.www.nypl.org/research/chss/grd/resguides/gay/index.html

Stonewall Library and Archive (Fort Lauderdale, FL)

http://www.stonewall-library.org/