In my AdSense account, it says: "When an advertiser who signed up for Google AdWords through your referral spends $5.00 (in addition to the $5.00 sign-up fee) within 90 days of sign-up, you will be credited with $5.00. When that same advertiser spends $100.00 within 90 days of sign-up, you will be credited with an additional $40.00. If, in any 180-day period, you refer 20 advertisers who each spend more than $100.00 within 90 days of their respective sign-ups, you will be awarded a $600.00 bonus. * * A Google AdWords referral is counted only for advertisers never previously enrolled in Google AdWords. You may only receive 1 bonus payout per year." Looks to me like an affiliate program...