Two ebooks from Seth Godin
Seth Godin has posted two free ebooks on his site. The first, Knock, Knock, is about the importance of landing pages--or rather, the various elements that make landing pages so imporant-- a clear call to action, design cues and what they say about your business, meeting audience expectations, etc.
The second, titled, naturally, Who's There?, sets the stage for why blogging is such a powerful marketing tool, and outlines a few important principles for how to (and how not to) publish a blog.
You should really subscribe to Seth's Blog-- he is one of the sharpest minds in blogging today. Too bad he doesn't work with individual companies...