Message boards are simply threaded discussions on the web. They are very similar to newsgroups, only they are nowhere as difficult to set up as newsgroups. Generally creating a new newsgroup is a long and painful process, while creating a new message board can take as short as ten minutes. You will also maintain much more control over the content with one of these boards.
If you want to create a forum for people to discuss things related to your web site, then you should consider creating a message board using one of the services described below.
A service which allows you to create extremely powerful message boards. You can attach these boards to your site. This is a cool (no pun intended) way to get some additional traffic, and give your visitors a place to communicate with each other.