Google launched AdSense referral program. Referrals is a feature of AdSense that allows you to increase your revenue, while increasing your users' awareness of useful products and services. By adding a referral button to your site, you can direct users to products like AdSense and Firefox + Google Toolbar. When your referral connects a user to AdSense or Firefox, you can generate more earnings while helping new web publishers monetize their websites or improve their web browsing experience.
When a user you've referred to AdSense first earns US $100, Google will credit your AdSense account with US $100. When a user you've referred to Firefox plus Google Toolbar runs Firefox for the first time, you'll receive up to $1 in your account, depending on the user's location.