If I have learned one thing from Dave Burke, the guy who “runs just about the most polite blog in the entire blogosphere”, is that you should reply to each and every person who takes the time to leave a comment on your blog.
Daniel from Daily Blog Tips suggests to Send Thank You Emails to each first time commenter and to those reviewing your blog or leaving comments. In fact I received an email from Daniel after recently leaving a comment on his site for the first time.