Free Message Boards and Forums
This is a free message board host that features a number of customizations features such as skinning and custom menus. Polls, smilies, and UBB codes are supported. See the website for a demo and full list of features.
You can get your own free, totally customizable message board for your Web site. Board is hosted at your own subdomain (http://YOUR-NAME.proboards.com)
InvisionFree is for those looking for a feature filled board with prompt support at no cost. The setup of your board takes only a few moments and frees you from the hassle of installing software
Bravenet offers a wide variety of web services including free boards.
Free board support by advertising.
Free customizable forum.