My daughter is an avid reader, usually to be found curled up with a book if she has the choice. Her favourite author is Jacqueline Wilson, author of the Tracy Beaker books among much else - a name which should be familiar to any parents of girls aged from about 7-13. Jacqueline Wilson has an official fan website to which my daughter is signed up, but in August she went a step further and sent a fan letter to Ms Wilson.
I expected that at most she would get a printed form-type reply; imagine then her delight to receive a hand-written postcard from JW herself. I have never seen her quite so excited. The card is now her single most treasured possession.
From the fact that JW has had a card printed (it shows the author in front of a shelf-full of her books), I summise that she replies in person to most if not all of her fan-mail, which must be a huge effort. I heard from people who have attended her signings that she is meticulous about dealing attentively with her fans in person too. What a pleasant thing it is to encounter a successful person who is willing to 'give something back' to that extent.