Chat-Forum - Provides free java based chat rooms.

Cyber Survey Engine - Create surveys on your site.

Everyone.net - Add chat rooms and customizable communities to your website for free. (****)

HearMe - Add a voice shat room to any site.

Inside The Web - Message board service from Looksmart with over 70 topics.

PForum - Custmoizable message boards from MercuryWare.

Suite101 - Discussions, articles, message boards and resources in a variety of categories.

vBulletin - Add and customize message boards on your site. (****)

What Helps - Set up or use online communities on your site.

World Crossing - Offers conversation and threaded messages public forums.