KBMentor
KBMentor is a script which lets you set up a knowledgebase system on your site. Unlimited number of categories, subcategories and articles gives your site the structure you want. Furtheron, you have full control over the layout, as the system supports templates. Works with Microsoft SQL Server, Access and MySQL. Themes and multiple languages support. Great admin interface with WYSIWYG editor. Articles can be rated/commented on and contain links/attachments/related articles. In latest version the browing tree can contain icons (can be different for open/close state), tree can now also contain articles. Perfect for building a documentation site. Print an article - or ALL articles in a certain category (perfect for manuals!).