I'd like to be able to do a forum like this that has a bar on the left that would take you to different forum sections then once in the forum sections there would be a sub category section that would filter the posts.
example: if the forum section was about easter eggs then the sub category section just above the posts would be broken down into red, blue and green eggs. it would filter just as in the "forum like this" example.
What forum software would I use?