Flexicontent

Flexicontent runs on Joomla and replaces Joomla's default section, category and article system. Flexicontent is actually a powerful content construction kit ("CCK") providing administrators flexibility and power similar to Drupal but with the ease of Joomla!

When your site is running on Flexicontent, you can nest unlimited categories, choose multiple categories and tags by article and format articles consistently with custom fields and templates. Bottom line, you can run a huge website with a small staff using Flexicontent.