American Foundation for AIDS Research
"The mission of the American Foundation for AIDS Research (amfAR) is to prevent HIV infection and the disease and death associated with it and to protect the human rights of all people threatened by the epidemic of HIV/AIDS."--from amfAR's website.

AIDS Action
"AIDS Action...is a network of 3200 national community-based organizations and the one million HIV-positive Americans they help serve."--from AIDS Action's website.

AIDS Watch
"World AIDS Day December 01, 1999, a 24 hour worldwide memorial established in order to remind us the battle is not over."--from AIDS Watch's website.

The Centers for Disease Control and Prevention
This is not specifically an lbgt site, but has a search feature that allows the user to find information of interest to the lbgt community. "The Centers for Disease Control and Prevention (CDC), located in Atlanta, Georgia, USA, is an agency of the Department of Health and Human Services."--from CDC's website.