Some days ago Google announced in Google AdSense's blog, that there's a new referrals pricing structure. The new scheme is well explained in the blog post.
I hope this shift in incentives may really provoke a change. Until now it was a well known fact that referral ads didn't pay. I must say that I never ever earned any money from them, even though I tried them for more than a year (ok, my traffic is not much). I guess this was primarily because in the old structure, earnings would pop only if the referral earned 100 usd in less than 180 days, which in most cases this is not the case. Usually it takes more than that to earn the first 100 usd by using Google AdSense. There's a learning curve that usually takes more than 180 days to surpass the threshold.
The interesting thing is that if 25 persons are referred, and they all get 100 bucks, in less than 180 days, and they are elligible for payment, meaning the comply with Google AdSense TOS the publisher get 2000 usd, niiiice.
So, I'm giving it another try to Google referrals, I've added them to all of my sites. I'll let you know in some time if the new structure works for a humble guy from uruguay like me ;)