Open Question: How many jobs can be done by project, not hour.?

Well, I am thinking about getting a job that can be done on your own time. One thing I thought of is moving into houses that are a bit damaged, fixing them up and re-selling them for a lot more. Now this would take construction knowledge in some cases and building costs. What are some other examples of things like this, or even a career that offers a project based pay, rather than hour, yet still pays decently.