Here is a great list of books that deals with conversion optimization. Find them, read them, know them all. They are great. (Compliments of Bryan Eisenberg)

Psychology, Human Behavior, and Persuasion

Marketing, Branding, and Selling

Usability and Information Architecture



SEO, SEM, E-mail Marketing, & Social Media

This is a great list.  I have read many, and have many more to read.  Stay tuned for more great stuff.