This is a simple idea and possibly a cheap one, but that depends on what you do and how you implement it. Welcome to the profitable world of the Middleman business.
So what do you do?
You simply become the middle person between two other parties. These other parties are looking for each other. One needs some work doing while the other can do the work and is looking for clients. Or you offer a simple service which allows two sets of people to meet for fun like forums or webcam sites.