Much of what doctors do could and has been written as expert rule-based systems. You might find the 1980s Mycin program for diagnosing different kinds of infections interesting; it was said to outperform members of Stanford medical school faculty in the domain that it addresses.

One problem with this style of tech is that your program is only as smart as the rules you give it, and you need seasoned doctors to help put together this knowledge. Even if they had the time, what doctor wants to facilitate the commoditization and automation of his or her profession, the undermining of their voice of authority?

I also question whether regular people have enough common sense and medical vocabulary necessary to safely operate such a system on their own behalf. Seems like it would be a fertile ground for lawsuits.

http://en.wikipedia.org/wiki/Mycin http://en.wikipedia.org/wiki/Expert_system