on The Digital Reader:
Finding the right niche / genre / keywords to market your book, and then parsing the sales data once your ebook is on the market, can mean the difference between a best-seller book and one no one has ever heard of.
The following post details a couple lists of tools that authors can use to target their books through market research, and then track ebook sales once the books are for sale.
This list includes all the tools I could find in a thorough search, but if you know of a tool not listed please mention it in the comments. (under Nate’s original post)