Google Adsense team announced that they provide channels for referrals to publishers. This is a long waiting feature.
As it indicated, the publisher can track the perfomance of your referral units across different pages, sites, or topics. You can also use channels to determine whether one referral design works better for you than another.
Adsense for content, Adsense for search and referrals, they all have channel tracking features.
The publisher have more flexibility to use their AD spaces on their web pages. To better referral and get better earnings.
From Google Adsense:
What’s New – June 2006
Channels now offered for referrals
We’ve added channel support to our referrals feature to offer you more tracking flexibility. Now you can track the perfomance of your referral units across different pages, sites, or topics. You can also use channels to determine whether one referral design works better for you than another.
With the addition of channels, now’s a great time to try referrals. In the past few weeks we’ve added additional designs as well as text links. You can choose the product and format that’s right for your site, and get started earning by pointing your users to useful products and services.
Referrals at Help Center
Optimizing with Channels
Google AdSense is one of best way to monetize your Blog.