Essai is right, giving away free products is a great way to build your list. Put an opt-in box on your page where people can sign up for a free 5 day mini course with supporting info for the product your selling. Many people will opt-in who end up not buying your product, which also gives you the ability to continue to try to market to them for your product.

For example on most sites I have 2 lists, free opt-in users, and purchased opt-in users. If someone signs up for the free mini course they stay in that list, however if they ever decide to buy the product, they will automatically be moved over to the purchased list.

This way I can not only market to them, I know which users are buyers and which ones are not. I can also send discount offers to the free opt-in users to try to persuade them to purchase as time goes on. Once they purchase they get moved to the purchased list, so they will never receive another discount offer for that product again. I can now market to them according to their new status.

Hope that makes sense…