Why more merchants aren't taking advantage of performance marketing remains a mystery - at least to me. Fortunately, there are some exciting startups emerging which can make short work of the challenges presented by affiliate marketing. Case in point, Refer.ly.
The platform, which enables consumers to earn rewards for recommending products to their networks, has just released an API which will help merchants (or anyone with a website) create an incentivized referral program to drive new business. In my experience, consumers aren't really designed to drive any substantial amount of traffic on their own, but for merchants this may make a lot of sense as all those shares add up over time.
The service is open to all merchants, but expect those in the software-as-a-service business and others to explore the options more closely in the future.