How to add a newsletter subscription form on the Facebook page?

Update: As per changes in Facebook's policy from March 2011, new FBML apps can no longer be added to Facebook. New signup forms will have to be added using iframes. Please follow this tutorial for assistance. Benchmark Email will soon be featuring a new method for adding a sign up form to Facebook. Please check back shortly for this update. (Note: If you currently have an existing FBML signup form