Because she listens.
I posted a review of her book, Brazen Careerist, on my personal blog (as well as this one) and she wrote a comment.
You know what that says to me?
She's scanning the net for discussions about her. She's listening to what people are saying. She's participating in the conversation.
And when she does that...
She builds the relationship.
Which makes me like her more, which makes me more open to reading her next article, book, etc.
Which makes me want to tell people (as I am doing now) about the fact that she listens (because it is so unusual).
Look how many books I've read in the past year. Then, look how many authors have commented on the review.
That's why I love Penelope Trunk.