On this post, a commenter writes,

I was thinking of providing my children with exceptional tutors from various disciplines in addition to their regular curriculum. Aristocrats would frequently engage proven scholars to teach their children. Good private schools today attempt to do the work of locating good teachers for you. There are plenty of extracurricular tutoring opportunities. How in the world, though, would one be able to locate and employ extraordinary teachers on an individual basis? Are there agencies that specialize in such activity?

What an intriguing business idea! I personally would like to teach in the old-fashioned style, where you mentor students rather than address them in a classroom setting. I could see a broker serving to find students who are able to learn from mentors (I think the student has to be fairly self-motivated) and suitable mentors in various fields.