American Guild of Organists: The national professional association serving the organ and choral music fields. Membership details, vacancies, publications, and a young person's guide to the organ. Extensive site includes many links

ATOS: American Theatre Organ Society: News, history, locations, articles, event calendar, artist directory, and local chapter listings. Not geographically limited to the United States

Gottfried Silbermann, Master Organ Builder: Photos, historical detail, locations of 31 original instruments, a visit to the Silbermann Museum, Silbermann organs on CD, contact and accommodation information