Seth Godin's is one I follow with interest. He's a leading exponent of 'Permission Marketing' and someone I really enjoy reading. Have a look at this.....a favourite marketing book of mine - can the church learn from this?
Permission Marketing: Turning Strangers into Friends and Friends into Customers
He takes away some of the mystique of marketing and writes in a very engaging way. His blog is worth a read and taken in a church context might provoke some discussion/ideas!