From Drupal and Moodle, right through to a Git versioning system and Perl modules on CPAN, we contribute back to over 175 community open source projects. This list is in order of the number of projects contributed to.
Mahara is a user-centric Open Source ePortfolio System based on an Artefacts, Views and Groups framework.
Koha Library Automation Package (http://www.koha-community.org)
Koha is a Library Automation Package (Integrated Library Management System) released under the General Public License (GPLv3 or later)
Moodle is a learning management system for producing Internet-based course Web sites. It is written in PHP and easy to install for use on Linux, Windows, Mac OS X, SunOS, BSD, and Netware 6. It has been designed to support modern pedagogies based on social constructionist theory, and includes activity modules such as forums, chat, resources, journals, quizzes, surveys, choices, workshops, glossaries, lessons, and assignments. It has been translated into over 100 languages, with more on the way, and supports the popular SCORM standard for content packaging. Moodle offers a free alternative to commercial software such as WebCT or Blackboard, and is being used by a growing number of universities, schools, and independent teachers for distance education or to supplement face-to-face teaching.
Work Request Management System (http://andrew.mcmillan.net.nz/node/90)
The Work Request Management System (WRMS) is used for managing requests from clients through to resolution and time recording for billing purposes.
This is a clone of the Totara source code (which is based on Moodle)
Mahara (contrib) (http://gitorious.org/mahara-contrib/)
Third-party contributed code for the Mahara e-portfolio system. This code is not supported by the Mahara Team but is graciously provided by other members of the Mahara community.
Drupal (contributions) (http://drupal.org/)
Drupal is an open source content management platform, allowing an individual or a community of users to easily publish, manage and organize a great variety of content on a website. Equipped with a powerful blend of features, Drupal is able to support community sites, blogs, portals and more. This is the contributions repository containing contributed modules, themes, translations and installation profiles. You can find the Drupal core project at http://ohloh.net/projects/3189. Since drupal.org moved from CVS to Git, this summary contributions project is no longer representative of contributed activity because each project has its own repository instead of one, large shared one. Ohloh added a Drupal contributions logo for maintainers to list their projects separately.
Koha Migration Toolbox (https://gitorious.org/koha-migration-toolbox)
A collection of scripts and tools for migrating from legacy library systems to Koha.