We rely on a host of tools, such as IRC (Internet Relay Chat) to communicate, Helga for web-based project management, mailman for our mailing list, SVN for version control, wordpress, mediawiki, etc. For animation (and film editing, lecture slide creation, etc) we turn to the famous 3D suite Blender, backed up by other great projects such as GIMP, Inkscape, FFMPEG and Ogg. Urchin and many of its team enjoy the use of libre operating systems such as GNU/Linux and BSD.
Python scripts designed to run in Blender, as well as utilities/ shell scripts we might write to aid production.
We are using Blender 2.5 beta, which means that we've written many scripts that have to keep pace with development changes. Ones we are not working with at any given time may not be actively maintained. The community can access an svn repository of all our code, and is welcome to submit patches for benefit of all.
Expounded : Blender 2.4x theme seen in many of my screenshots