I am sure, at one point or another, you have you have received a referral marketing type offer from a company you’ve worked with. I certainly have been getting these on an ongoing basis. The most aggressive ones have been those from DirecTV, and they advertise their offer on their website as well:

Last week my propane supplier got into it too, and I received the following flier with my newest AmeriGas bill:

In a sense, affiliate marketing is exactly that (referral marketing): when there is a sale/lead referral, the referrer gets paid. But in most cases affiliate marketing is actually a tad better: it’s not a store (or an account) credit that you get, but real pay/cash. I would therefore argue that it is not the referral marketing that is the most powerful form advertising but affiliate marketing (which may well be treated as your next level/new generation referral marketing).