currently i'm creating an mlm system for a company in Utah. There are several different kinds of programs that can be created, bianary, forced matrix, 2 level tree systems 3 level tree systems. Some company's function off affiliate based marketing only. The trick is which algorythms to use and how to effectly manage large amounts of data in a database. These days it seems like a lot of companys want to build their own system. I have seen dozens of systems for sale, and have personally tried a bunch of them out. Though, just because someone elses system works a certain way for them, doesn't mean that it will work for everyone. This is the trick of building this kind of system. Change the number of levels or the way in which you process commissions in one way or another, and you could potentially be changing a whole infrastructure or several thousand lines of code.