Denny's has a "Father's Day Card Maker" on their Facebook page (http://www.facebook.com/dennys?v=app_10531514314&ref=search). Use it to create your card and you can get a free Ice Cream Float!
You have to print and present the "email" and you have to purchase a meal/entree to be eligible. One coupon per check per visit. But it can be used between June 20 and June 27, 2010.