This video is about wikis, but it really applies to most Web 2.0 tools, blogs, forums, podcasts, wikis, and social networks. Users collaborate to create content.
Our two main insideCatlin tools, Moodle and Drupal, both provide wiki-like functionality. To create a course wiki in Moodle, Turn Editing On -> Add Activity -> Wiki. In Drupal, most items can be edited by anybody, especially the page and book content types.