One-Step Greeting Cards
All-In-One Card Stamp Saves Time, Money and Hassle
All you need is a stock of white blank cards upon which to press the stamp. I suppose it wouldn't hurt if you also added your own personal touch with a note at the bottom.
Implications - This is the kind of product that will help you out, if you're a funny guy. Your friends will buy into your obvious gimmick, and you'll earn points for eschewing traditional cards in favor of a hilarious one. Win-win.