I'm not really convinced that StackExchange is the best system for that. You'd really want one StackExchange per person; otherwise, the one-answer-per-question nature of StackExchange, with voting for "correct" results, which result in bizarre gaming behavior and impossible-to-follow discussions.
You could use the tag system.
The questions would be at ama.stackexchange.com/questions/tagged/Joel+Spolsky. The person who posted the question just had to accept the answer of the person who he had asked.