I find social media amazing. I'm in the middle of a book I'm really enjoying, and went to google to see if there's another in this series and when it might be out, and lo and behold I discover the author's twitter. She replied in under five minutes to my tweet (must have caught her at the right time), and we went back and forth with a few tweets. That's an author who, while clearly promoting future endeavors, is taking the time (even if it's an assistant I don't care) to be in touch with fans.
A couple weeks ago I tweeted another author who clearly was answering her own messages... it took her about three weeks to get back to me... but I don't care... she replied!
Susan Elizabeth Phillips has a current question of
"Can any of you guess the number one way authors grow their reading audience? (Other than writing a great book.)"
I'm thinking it's word of mouth, but she'll have to get back to me on that.