It's easy to imagine that when Steve Martin was at the height of his powers, he received a good deal of fan mail. That's not to say he doesn't deserve it now - just that when he was basking in the beauty of "The Jerk," he was probably rolling in letters from admiring fans.
Turns out Martin had an awesome, and efficient, way of responding. Mad Libs-style. As you'll see from this "personal" letter written on his production company's letterhead, Martin really was on top of his game. (via Letters Of Note)