FFA stands for Free For All page. The entire purpose of an ffa page is to allow your visitors to come to your ffa links page and place their advertisment for no cost to them.
Web surfers including webmasters are a funny breed.
We are always looking for something free. FREE we will keep coming back. When your visitor comes to place her ad she must fill out a form on your links page which ask her for the URL, description, and her e-mail address. On this very same form there is an agreement stating that you will send her a confirmation of her posting the link and another message notifing her when her link rolls off the page. This is when you include your sales message.