From Mahara Wiki
Note: If you are looking for plugins to download, you can browse a list of them at http://wiki.mahara.org/Plugins
Mahara has a highly pluggable architecture. Currently, you can write plugins for authentication, content types (artefacts), blocks, notifications, search and more. In addition, you can theme Mahara, and also translate the UI to different languages.
- The Mahara Architecture Introduction series of articles gives you a general introduction to how Mahara is structured, and where plugins can go and what they can do.
- The Mahara git repository policy details how repositories on git.mahara.org should be structured, and how you get one should you want it.