Clickbank is a marketplace of digital products (software, information, etc.). What’s handy about the marketplace, in terms of generating content ideas, is that they list products according to popularity.
Of course, that is not a foolproof way to see what topics are most popular (as opposed to who has better marketing/copywriting), but it can help you put together some possible ideas and observe the marketing and sales copy of those top sellers as well.
To search ClickBank, navigate to the Marketplace at https://www.clickbank.com/marketplace.htm and you’ll see the categories on the left side.
When you click through to a category, you can then sort by “popularity”, which is the default. Sorting by “gravity” will also help you determine some idea of popularity.
You can also search by using keywords and search the entire marketplace or just the current category. You can also choose English, German, Spanish or French from the dropdown box: