In this thread, there's a comment I found in writing this question, which makes a good point:
I can see a very good use of this engine in professions other than computer programming: Lawyering, Medical Advise, Education...well, to be concise ANY type of counseling service. And, those communities would like a number of features that even SO would be benefited.
I've been thinking about this as well, and it seems clear to me that if people in other fields can be roused to use a community site such as this to solve their problems, it would be of great benefit.
And though a site like SO seems to work best for objective questions, it can also be used for good discussion and subjective questions (as meta-SO shows). Even the domain of "general advice" can take advantage of the SO engine, where now, you might ask questions in some phbb forum, or the advice column ("Ask Cathy") in the local newspaper (or go to a professional counselor, though that's probably a better option if possible).
The main challenge in making this work for non-computer-related fields is getting knowledgeable users. For SO, SF and SU, Joel and Jeff could leverage their existing readership to give the site a real boost to start with, with enough momentum going to really become popular. And this site thrives on network effects. Doing something similar for other fields would be more difficult.
You may not even be able to recruit users through Google nearly as well as the SO family does, since programmers are much more likely to scour the web for answers to problems compared to, say, doctors (you'd probably want to change your doctor in fact, if he/she was using Google for diagnosis). On the other hand, you might find many amateurs trying to find answers, such as people who do in fact use the internet to try to diagnose their own diseases. With reputation added in, this can be a good thing.
Who else thinks it's a good idea to expand the domains this type of engine is used for, and why (or why not)? And what sort of challenges would be faced in doing so? What's a good way to go about making this happen, and who should go about it?