I was intrigued by an article about a tool that maps online discussions, allowing teachers to track a discussion, not just for grading but for teaching. The screen-shot on the developer's homepage says it all. Any chance there's a code-slinger out there who can throw this into Moodle?
Unfortunately, I can't oblige with the code, but I think it would be a great addition to Moodle. Their mission statement does indicate openness.