Adsense Publishers can now track the success rate of product referrals on specific pages or 
websites as the channel feature is now available for referrals like Picasa, Firefox, Adsense and Adwords.
You are allowed to create upto 200 active channel names for Referrals. To add a channel to existing Adsense Referral code, either overwrite the code with the new version or just append the following line: Adsense brings Channels to Referrals » Digital Inspiration © Amit Agarwal