Today a lot of start up companies almost totally rely on affiliate sales as their main source of income. I dont think I am alone having these thoughts. Many merchants are also picking up on this. This tracking is essential for an affiliate to get paid. Commissions on repeat sales is still rare though.
Lets look at a couple of examples of residual income programs.
IMC, a successful affiliate marketing program says they track a visitor for up to 5 years and also pay yearly residual commissions. Meaning you get a commission from a referrals all future purchases. Almost all Webhosting companies have affiliate or reseller programs. If you refer a customer you get a monthly cut of their monthly hosting bill. Commission Junction have 170 merchants and bundles all commissions from their merchants into one single check.