The google adsense referral program was never that good in my opinion. The conditions for getting a qualified referral were tough and the payouts were poor. Nevertheless, they got hundreds of thousands to sign up to refer new users to Google Adsense.

Today Google announced that they are removing the Google Adsense referral program

Hello,

We are writing to share some important information with you about
referrals to the AdSense product. As part of ongoing efforts to
optimize revenue opportunities for our publishers, we’re
constantly experimenting with new revenue-enhancing features as
well as tweaking those products already available to our
publishers.

This is the case for referral units directing visitors
to sign up for AdSense. After experimenting with this program
over the past year, we’ve concluded that there are other products
that are of higher value than this program to publishers in your
region. As a result, referral units for the AdSense program will
be retired in the coming weeks. Referrals to other products and
services remain unaffected.

If you’re currently displaying referral units on your site
directing users to sign up for AdSense, read on below for details
about what to expect in the coming weeks.

In early January, the option to add referral units directing users
to the AdSense product will no longer appear in your account. You
will continue to accrue earnings for all existing referrals yet to
generate $100 until late January, at which point the program will
be fully retired. Existing referral units will continue to appear
on your pages.

By the end of January, you should remove all referral units
directing users to AdSense from your pages. Referral units
that you do not remove will continue to be displayed on your pages
as normal, but conversions will no longer be recorded. We
suggest you replace the AdSense referrals with referrals to
another product or service or an additional ad unit.

Thank you for referring users to AdSense in the past. We
apologize for any inconvenience this news may cause.

Sincerely,

The Google AdSense Team

Google Inc.
1600 Amphitheatre Parkway
Mountain View, CA 94043

If you have Google Adsense referral banners on your website or blog then remember to make a note to remove them