Sakai community.
Extending Sakai with Community-Contributed Tools
Taking advantage of the Sakai project's open architecture, many community members develop and publish Sakai-specific tools and innovations known as “Contrib Tools.” Freely available as contributions to the community, these tools are tested, documented and released under open licenses for anyone to use, but they are not packaged with the core Sakai product release. Popular Contrib Tools are sanctioned by the community and considered reliable and of high quality. In fact, often the expanded features and innovations of Contrib Tools eventually become incorporated into the Sakai Core Tools.
You can view descriptions of the most popular Contrib Tools on the Sakai feature list, and more information is available on the community wiki.