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.
colinsc's koha (http://github.com/colinsc/koha)
backup of koha development and experimental branches
A web based front end for Capistrano
PLEASE CHECK http://github.com/lifo/docrails/wikis
eMusic/J is a cross-platform download manager for the emusic.com service. Custom versions of it are also in use by Classicsonline and Reggae Country.
Epiphany Extensions is a collection of extensions for Epiphany, the GNOME web browser.
A client to go with my nodepp application
For code related to making ePub files
A complete packaging of Evolution Data Server for Maemo, including the addressbook, calendar, and email library (Camel).
Faker (aka fake-factory) is a Python package that generates fake data for you. Whether you need to bootstrap your database, create good-looking XML documents, fill-in your persistence to stress test it, or anonymize data taken from a production service, Faker is for you.