Clubs are like sub-communities, with their own content and resources, and can be managed by regular members without requiring administrator involvement (and thus, no need to use the AdminCP). Let's say you run a site about video games and someone wants to be in charge of a particular game (or gaming series). Instead of you making an individual forum, blog, gallery, and downloads area, as well as granting them moderation privileges for those areas, the user can make a club. From a visitor perspective, jumping around the site to get from one area to another for the related content (say from forum to gallery), it requires a few clicks, or special links that, again, require ACP access to control. Using a club to control it, it's all right there. It also allows the user to control who is in the club, etc, without having to bug admins to make changes.
