I know I'd like to get one of those "prizes" that it mentions. A biomechanical weapon of destruction or one of those little metal "clicker" things they used to have in Cracker Jacks would be topmost on my list
Basically it's a way of "getting the word out" regarding the emuforums board. By using a special link to the board's registration, you could get credited for new people that sign up. Had the admins chosen to allow for it, people with a certain number of referrals could win prizes or get some sort of special offer or the like. Of course (so far as I know, at least), we don't have such things here.
To be honest, it's probably best that we don't, seeing as how whenever I see something about "referrals" on the Internet I'm made to think of AllAdvantage :shudder: