I've seen it work in the past, and I want to try it for my own site I'm developing... a game site somewhat like mobsters on myspace... but I want some feed back on my idea. I was thinking that as apart of the game, users can earn something in the game for referring other people to join. The problem I'm facing though it that some people will have resources to refer a lot more people than others. What would give people incentive to refer friends, yet make it fair. Thoughts?