I think this would be a cool idea and possibly not to hard to make, for someone who knows what they are doing.
You know those "quiz your friends" sites? I would like one of those built into phpbb.
So you set your questions, and multiple choice answers to each one. For everyone who takes the quiz, the results are shown at the top of the post similar to the way poll results are displayed.
Maybe the results are only shown to people who have taken the quiz, and the person with the best score gets a prize. Points or something donated by the person who made the quiz.
Great idea or what?