Link to your book's Amazon page, as opposed to -- or in addition to -- other outlets. Ironically, the more books you've sold on Amazon, the more books you're likely to sell on Amazon -- since their search brings up the best-selling books first.
Enter keyword tags. On your book's Amazon page, under "Tags Customers Associate with This Product," you and other users can add keywords that will help people find your book in Amazon's search. These should be tags that are relevant to your book's genre, content, and themes.
Join the "Search Inside The Book" Program. This feature allows Amazon users to view the contents of your book directly on their website and lets your book show up in keyword searches. You can specify how much content you want viewable -- users can search inside or simply view the table of contents and back matter.
Get customer reviews. If you know someone who simply loved your book, ask them to do you the favor of putting a positive review on your Amazon page. You can also add this request to your website and at the bottom of enewsletters pertaining to your book.
Write reviews for other books. This allows you to get your name out there. In your profile you can specify your title as "(Your name), Author of (Your book's title)."
Blog. You can link to an outside blog you already write using RSS. Go to Author Central on Amazon to add your blog. Future posts will then appear on your Author Page, where readers can find updates about your work.
Create lists. ListMania and "So You'd Like To..." are two ways to create lists of books that you categorize with a title of your choice. Users will see these lists appear on other books' pages, along with your name.
Post in the Forums. You can connect with fellow authors and readers -- they'll be more likely to show interest in your book if they know you personally. Avoid posting advertisements for your book (first-published announcements are okay) since this is synonymous with spam and may irritate readers so much they go out of their way to avoid your work.