Hello, I am a student of University of Sao Paulo.

We used Moodle Online Judge Plugin in some tasks of Object-Oriented Programming classes.

To improve the activities I did a small change in your code. I added the following options for activities:
-Insert a preamble in a code;
-Insert a postamble in a code;

With this options the teacher can add some pieces of code in all tasks sent to the activity.
In University of Sao Paulo, we used this options to establish the main function for all students. So, we can evaluate if the student used correct programming techniques like heritage and polymorphism in Java. It isn't possible with only output comparision.

I have released these changes in a google code repository http://code.google.com/p/moodle-online-judge-changes/
However, I think it would be interesting if these changes were made ​​by you, who built the entire project. So I want to make this suggestion to you.

Another suggestion is a plug in to use the online judge as a question type of a quiz in moodle. That would be interesting why moodle add all activities to grade board, and several times we use your plugin for a non-evaluated activity and in actitivities with more than one exercise.

It is a great project, thanks.