The Marketplace is an organized directory of over 10,000 of ClickBank's most popular products. These are listed in order of popularity across a number of categories. The benefits of the Marketplace are
Vendors can list their products here and have a potential audience of 100,000 affiliates to promote them.
Affiliates can search for individual products that they wish to promote, or promote the Marketplace as a whole.
Here is a definitive guide to the MarketPlace