We have been working with moodle, and modifying it considerably to be used as a complete online training platform. More details on our features can be found here and here. We started thinking of open sourcing some of our code, when martin appriciated our implementation. This might be useful to the moodle community.
This is my repository, https://github.com/ankitml/moodle2.2. Would love to hear what moodle community thinks of this implementation and some guidelines on how can plugins / modules be created from this codebase.