Chris The Story Reading Ape's Blog
on The Digital Reader site:

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.

