WordPress and its Plugins
Using Asgaros you can also create a microblog within wordpress. It allows Forums and Topics to be Embedded in any page. Even a guestbook and shoutbox where the public can post messages. Guest posts Topics can be moderated but not the replies.
Yada Wiki is a free plugin for the WordPress content management system. Yada Wiki provides a wiki post type, custom tags and categories, a table of contents option, and a sidebar widget. The plugin allows you to link your wiki pages together using the titles of the wiki pages.