This is a bit postmortem, but you may be interested in knowing that Google has decided in their infinite wisdom to shudown the AdSense Referrals program All AdSense Referral ads have stopped working as of today if I’m not mistaken.
Although some people always criticize Google, I think that in this case Google made the right decision. The referrals program was a dog; put simply it just did not perform. My personal experience with the referrals program wasn’t all that good. I noticed that my referral earnings were very weak when compared to pay per click AdSense ads. The conversion rates were low, and when I did get a conversion it would pay out quite poorly. My impression is that the referral program worked best for advertisers but not for publishers.
So, R.I.P AdSense Referrals program, you will not be sorely missed.