American Sociological Association - Founded in 1905, this is the chief professional organization for sociologists of all subdisciplines within the United States. Its emphasis is on providing the application of sociological analysis for the benefit of society. Useful features include the "code of ethics" and a list of publicly available data sets.
International Sociological Association - Founded in 1949 under the auspices of UNESCO, this organization seeks to provide international communication and cooperation in sociological research. Its research committees cover 53 areas in sociology. A list of relevant periodicals is also featured, some with access to back issues.
North Central Sociological Association - Covering seven states and the province of Ontario, this is the premier professional group for the sociologists of the Midwest. A listserver here serves as a regional discussion forum.
Pacific Sociological Association - Established in 1929, this organization provides a professional forum for sociologists in the western United States, Alberta and British Columbia. An index to current and back issues of The Pacific Sociologist is provided.