As it is now, the forums feel like an add-on to Drupal. This actually is the case with many CMS solutions. Instead of integrating with the content and being a place to discuss the content, they are a back-page type of thing which allows people to talk about "other-stuff".
What I propose for the forums (and what I've always been looking for in ANY CMS) is to where the forums are completely integrated with the rest of the site and are the center of discussion.
As it stands now, articles, stories, etc are discussed through comments. Now comments aren't bad, but they encourage users to just post their initial thoughts, read others, and never come back. Forums on the other hand, often lead to in-depth interactive discussions.
And this is a major problem. Often forums on sites seem empty while their front page is full of content. You could always just make a forum post, paste the text or link of an article into it and say "hey, let's talk about this", but isn't that redundant when comments are essentially replies to a forum post?
What I'm suggesting is that forums become "discussion containers" so to speak (not literally). The comments of any type of node should be tied to forums. And the forums themselves should simply represent categories, and not seperate sections.
So for example, lets say I post an article about Halo 3 which I put under my "Xbox 360" and "FPS" categories. This article should automatically by listed in the forums, which would consist of "Xbox 360" and "FPS" and whatever other categories I have. Let's say I also post a poll under the "Xbox 360" category. If I'm a user and decide to browse through the "Xbox 360" forum, both my original article about Halo 3 and the recent poll would be listed as forum topics in the forum itself. So any user could go through and discuss in the forums whatever they'd like.