PayPal home page in 2000. PayPal grew quickly due to a viral referral marketing (get paid to sign up, and then get paid more to refer friends). An outline has been placed around the get-refer promotion.
Bridge Store example: On a retailer's Bridge Store, a merchant will soon be able to show a give-get referral promotion like this to registrants (e.g. brides). The registrant and recipient can both earn $20.