Who's There? - by Seth Godin
Seth Godin's Incomplete Guide to Blogs and the New Web
This is a free pdf Seth Godin produced in 2005. The ideas in this eBook are probably even more relevant today, and apply to blogs, podcasts, and other means of content production where your aim is to build an audience. Seth takes us through the four objective we should have and gives us four laws to follow with our blogs or podcasts.