Merchant looking for creative ways to research what products to sell to affiliates

Affiliates have their “system” of how to research their niche including making sure they have interesting products to sell with an adequate commission for their efforts. So far I have been learning how to research from an affiliate point of view but now I want to spend some time researching on the other side of the equation before deciding on a battle plan. From the side of a merchant that does not yet have a product and is considering producing a product but I want to find the need first before starting.

There are products that I can have private labeled and that I already have some experience with years ago and now I want to start up again but by market online through potential affiliates that desire the products to offer. Other than going to Clickbank or Share-A-Sale and looking for the top selling products, are there any other software or utilities that would give additional indicators (again from a merchants point of view) of which niche products that have room for more competition ? Other than looking at the top selling products, what other sources for data (or tricks for using the most popular data) can I analyze so that I know in advance what will draw a good audience of affiliates ?

The only thing that comes to mind is seeing the volume of sales compared to the number of suppliers of that type of product along with identifying which ones allow a very attractive commission. What other indicators I can look at ? What web sites or tools for merchants exist to give me data like this ?