This page contains links to professional groups that may be of interest to technical communicators.
The Usability Professionals' Association (UPA) is an organization that may be of interest to anyone involved testing usability of documentation, online help, or computer based training.
The American Society of Indexers (AS) advances indexing, abstracting, and database building.
Boulder Writers Alliance (BWA) lets you search their online membership directory (for example, search for writers with certain skills).
The Association of Computer Machinery (ACM) SIGWEB is the special interest group on Hypertext, Hypermedia, and the Web.