Association Central
Locate associations by keyword or find contact information for a particular association at this commercial gateway to associations.
http://www.associationcentral.com/

Associations on the Net
A listing of associations by subjects from the Internet Public Library.
http://www.ipl.org/div/aon/

American Society of Association Executives Directory
A directory of over 6,000 associations, searchable by category or location.
http://www.asaecenter.org/Directories/AssociationSearch.cfm