A Facebook fan box is a box that you can add to your website that allows your website's readers to keep updated on what your posting on your Facebook fan site. By adding a Facebook fan box to your website you're allowing your fans, blog readers, customers or friends to see what's going on at your fan site from your website.
Adding a Facebook fan box is easy. First go to your Facebook fan page and click on the link under your profile photos that says "Add Fan Box to your site".