Banana Dance is an open-source PHP/MySQL-based program. It is designed to combine the simplicity of wiki-publishing software with the versatility of a CMS. The program also promotes community-building through organized and user-rated commenting features.
** http://www.bananadance.org/

Wiki/CMS Combination
Create categorized articles.
Custom settings on all articles.
Compose webpages with a simplified wiki-style design, or use full HTML.
SEO-friendly publishing.
Easy and accurate article searching.

Community Building
Easy user registration with custom fields.
Customizable user types with unique commenting, article creation, and administrative privileges.
jQuery-heavy code for less reloading and more dynamic content loading.

Commenting
Threading for logically laid out comments and replies. Select either "tree-style" threading or "forum-style" threading.
Rated comments based on upvote/downvote score. Hide comments under a specific rating.
"Comment Types" to logically organize and classify comments.
Option to require approval of comments for specific user types.
Limit who can comment and on which articles they can comment.

Website Integration
Preset themes for easy layout selection.
For more control, easily customization of HTML templates and CSS.
Create custom email notifications and templates.
Caching: Smart caching system to ease database loads on high-access websites.
Widgets and plugins to extend the program!