Shawn, I too am very interested in improving the classroom experience using the web. You might want to check out my buddy Mark's post on creating a viable blackboard alternative: http://www.markmcgranaghan.com/2006/12/16/idea-lightweight-blackboard-alternative/

He outlines pretty well the costs of maintaining blackboard for college campuses (very expensive) vs. the quality of its product (not so hot).

For some feedback, I think the automatic grading system is interesting but incredibly difficult to pull off. Teachers have a huge, vast array of testing practices and to create a system to easily check them would be very time-consuming. Maybe it'll work for very small cases, like multiple choice.

Also, building on top of other suggestions, I would separate the features from the reasons for making them.