The Internet is great at setting up exchanges.
These days, it looks like such exchanges are more and more coming into the worlds of education. For example, check out Learn2Lingo.com and notice that you can be a student and a teacher at the same time. Pay for courses…get paid to offer courses.
Learn
“The easy, flexible and affordable way to learn a language.”
Teach
“Give online classes and earn money in your spare time.”