Just a couple of books I've come across that I recommend reading, and then IMPLEMENTING the ideas they are presenting:
"Landing Page Optimization" by Tim Ash - Goes through the ins and outs of web page conversation. Lots of great examples from successful and unsuccessful websites including screen shots of what to do and what not to do. Discuss ROI for your landing pages as well. Excellent read and a very clear "how-to" guide.
Here's a video with Tim Ash explaining some of his concepts.
"Always Be Testing" by Brian Eisenberg - Introduces you to Google's Website Optimizer (it's free) and how to use it.
Why is this important? Have you ever really thought about how your website visitors see (or not see) the content on your website. For example, did you know about some of the visual tests that have been run on website reading patterns? Or about the concept of "Landing Page Eye Tracking"? You'll notice that these publications are a couple of years old, yet nearly every real estate agent website that I visit eschews these basic concepts.
Check them out or you might as well spend your time walking neighborhoods every Tuesday or sending recipe cards in the mail. You'll get the same result.