I maintain a website for a charity cause and would like to set up a system for promotional purposes.
You may have seen this before:
The user (visitor A) registers and is given a username. He/she invites a friend (visitor B) to the website with an email which is generated (this has already been set up). The email points B to the registration page where he/she enters A's username as the referrer. A is then credited with a certain number of 'points', and B can then do the same, and so on.
The points add up for different users recruited (and for other things done) and a league table is kept so the winner gets a prize. Each username would have access to a generated page telling them details like points earned, etc.
As I do this in my free time for free, I don't have the time to learn how to create this from scratch, so I was wondering if there are any scripts of any kind that do this or something similar so they can be modified for the purpose? If not how could I most easily go about doing this?
Any help on this topic would be greatly appreciated!