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.
Giving away a free informational product such as an e-book, an email series or a mini course is a popular tactic many affiliate marketers use. Usually, your readers will have to provide their email addresses to receive the product from you. You can then use this to sell to them via email marketing. Additionally, an informational product can generate interest in the actual product you're trying to sell. If your product is popular enough and brings enough traffic to your site, you could also monetize the traffic in other ways, such as AdSense.
Websites consisting mostly of affiliate links have previously held a negative reputation for underdelivering quality content. In 2005 there were active changes made by Google, where certain websites were labeled as "thin affiliates". Such websites were either removed from Google's index or were relocated within the results page (i.e., moved from the top-most results to a lower position). To avoid this categorization, affiliate marketer webmasters must create quality content on their websites that distinguishes their work from the work of spammers or banner farms, which only contain links leading to merchant sites.