If you’re the vendor, then you create your own product and set it up using Clickbank’s system. They then list your product in their marketplace so that tens of thousands of affiliates can see you. They handle the tracking using unique tracking links and cookies so they know exactly where the sale came from and credit the referring account accordingly.
I, too, have always looked at ClickBank as a secondary and even tertiary monetization source. But it can be a great sources of revenue. I linked one of my articles to a related product on CB, and without really doing promotion or anything unusual, I get a few sales a week. Mind you, the keyword(s) for the post aren’t that huge either. So, even though the traffic not huge on that post, it still manages to get some sales.
It's important to keep in mind that participants don't "qualify" for all surveys. Market researchers often want opinions from users who match specific demographics or who are in-market for particular products and services. If you attempt a survey that you ultimately don't qualify for, Swagbucks will give you at least one point in its rewards program. You know what they say: "A penny for your thoughts".