I also modified the moddle and build another web site at http://enjoy.phy.ntnu.edu.tw/
The physlet builder and other simulation builder (circuit builder, mindmap builder...etc)
are part of the editor in our moodle system. We also have SVG drawing system(However, it only work for IE now.)
So user in our moodle system can use editor to draw simple diagram, create simulations, mathematic equations ...
However, it was all implemented in Chinese. I did not have time to port it to different language version.