I wrote a letter of support to Ed Asner after his show Lou Grant got cancelled. He wrote a really charming thank you letter back.
A local celebrity, writer Dave Barry sent me back a card with a smart but appropriate comment when I wrote him about an article of his in The Miami Herald.
Also got a card from Carl Hiaasen after disagreeing with one of his opinion pieces.
I got a response from Surgeon General Joycelyn Elders after Clinton canned her for being honest and outspoken on teen sexuality. She wrote back and I think it is a personal signature.
You have to watch because so many celeb letters are written by others with a printed sig.