CataList — the online catalog of groups that operate using LISTSERV software. Browse more than 52,850 public lists on the Internet. A bonus: each list is shown with current number of subscribers. Google Groups — enables you to search for discussion groups in your career field by entering a keyword. Powered by the best search engine on the Web: Google.)
listTool.com — a free tool that makes the process of subscribing, unsubscribing and sending commands to 878 mailing and discussion lists (in categories such as law, art, music, computers, news, business, humor and more) easy. Search for lists by keyword(s).
Tile.net — a comprehensive list of Internet-based resources, including discussion and information lists, Usenet groups, and more. Browse by name, description, and domain.
Yahoo Groups — where you can join or start a group on just about any topic.
Yuku — (formerly ezboard) offers profiles, image sharing, blogs, and discussion boards all in one place. You can have up to five Yuku profiles.
Monster’s Career Advice Community — offers a wide variety of interesting forums that enable you to network on topics of interest to job-seekers.
Ask the Headhunter Discussion Boards — registration required to participate.
Alumni.NET — offers links to high schools and colleges located around the U.S. and the world.
Classmates — really four databases — high schools, colleges, military, and workplace. Claims to have more than 40 million registered accounts, including 3.5 million paid accounts. Easily locate old friends, coworkers, and more.
Reunion.com — includes more than 33,000 high schools throughout the United States. Alumni of any American high school can visit this site and register, update information, or search for an old classmate. This database can be used to locate a lost friend/acquaintance/business associate at a high school in any region of the country. Boasts 51 million members (growing by more than 1 million a month) and 700 million+ profiles.