How do you prevent customers from having to go through direct link downloads and checkout/payment processes for free products?

Hi guys, I sell digital downloads in my shop and want to add a section for freebies. How do you guys add free products? And how do you do it so the customer doesn't have to go through the whole checkout/payment process (even if the amount is 0?) if someone could please refer me to a blog or something I would appreciate it as I'd like to just do it myself. I know how to add a direct link download, but would prefer to capture customer info, so this is not ideal.