If you have an author page set up on Author Central at Amazon, it now shows you the number of books sold in each geographic region from BookScan, which includes sales not only from Amazon, but from Barnes and Noble, Borders, and other participating book stores. It does not count Kindle or other ebook sales, and has a disclaimer that it only accounts for about 75 percent of all book sales. Some book sellers are non-participating, such as WalMart and Sam's.
It is the coolest thing I have seen. You move the mouse over each state and it shows how many of your books were sold in that area. It shows the entire month of November right now, and tells you how many books total you sold each week. It says it is updated weekly, but I did not see any December figures on the map, although the bar graph is current up to the current day. (The bar graph only counts Amazon sales rank.)
It shows that a total of 19 copies of Gumbo Justice were sold in 14 different areas of the U.S. in the month of November, and shows each state and city area the books were ordered or purchased from. It also gives you a little chart next to the map that lists each area with how many books were sold if you are not a fan of maps.
There is a tour you can take that shows you how to find the info and what the information means, and if you're obsessed with trying to figure out how your promotion might be paying off each month like I am, this could be a great tool to help.
Jambalaya Justice, coming 2011