Google Adsense referrals allow publishers to earn extra money besides the cost per click contextual ads and the Adsense for search. Now Google Checkout Referrals have been added in addition to AdSense, AdWords, Firefox with Google Toolbar, and Google Pack.
Google Checkout is a fast, safe, and convenient way to shop online. Whenever someone clicks on your referral button, signs up as a buyer with Google Checkout using a valid U.S. credit card, and completes a purchase of at least $10 before shipping and tax through Checkout within 90 days – You earn $1.
Remember Checkout referrals are currently only available for U.S. publishers, and Google Checkout is currently only available for buyers with a U.S. credit card. Now that monetary incentive should give Adsense publishers the motivation to try out these referral units.
But I think the best deal is to refer Google Adsense which can earn you $5, $250 and even a $2000 Bonus! Instead of a few trickling dollars, I prefer to hit the jackpot even though it is rarer, especially since you can endorse these referral deals.