As in, is the forum the whole site, or just an add on to a main site? Of course, I count portals and article systems as forum based.
But yeah, mine is personally set up as part of a larger site rather than the whole site itself, just with a few main site features integrated into it. So is your forum the whole site, or just an add on/subdomain part?
My site is based around a forum, with a downloads mod, arcade, and some other things . My website is based on Counter-Strike Customization, so we need to use the forum a lot.
The forums are the main activity on our site, although we do have a news page as the ultimate homepage, and a very old index page from a previous url that many still use.