Where can a person go to find great gift ideas for Dad?

So where can a person find a good gift for Dad? One can simply visit the mall, and go to a store that reflects on Dad's personality. Is Dad a busy person with lot's of plans ahead of him? Buy him a stylish watch to match his personality. Is he that one funny, carefree guy? Simply go to a gag-gift store and buy him that pimp cup he's always wanted.