To tell you the truth, I find that the most reliable way to make money with such a system, is to create the system yourself. Like, I have a friend who was involved in this network marketing thing, and he tried to get me in. He was almost mad at me for a month when I told him I wasen't interested, but nowadays, everytime I ask him about it, he tries to steer the subject.
If you want to make money, you have to create your own system, and focus on delivering value to people.
For instance, just recently, I started creating and publishing apps for the blackberry smartphone, and so far, I made more money in 3 months, than I ever did eversince i've been trying to make money online.
However, if you go to blackberry's website in the developpers section, not ONCE, do they ever claim that you will get rich by publishing softwares for them, or even make money with them.
They'll use terms such as "Create compelling applications that push data to users [...] and much more.", but they'll never give you any figures on how much you should expect to earn, when they clearly know that an above average app can easily return $1000+/month in revenue for life.
Nothing sustainable ever comes from "ripping people off", or "getting rich from others", and stay away from any money making system that tells you upfront that you'll be making a lot of money with them, or even worst, that you'll be making a lot of money by putting in little hours and effort.