Amazon have improved their Author Central site where book authors can get some some data about sales sold through Amazon. Since I have only one book, An Introduction to Business Systems Analysis, I don't have much to look at. But I thought I'd share two pieces of information available: Total Sales, and Sales by Geography.
The information is for the United States only. First below is a chart of weekly book sales going back to February 2011 (about a year after the book was published by The Liffey Press) - a very modest 57 books in total have been sold during this time.
Next is Sales by region. The numbers are small, but New York comes out on top with 10, Chicago next on 5, and Phoenix on 4. The map that the screen grab below is taken from is an interactive one - you can scroll over each state (on Amazon.com only) and see how many books you have sold in each one. I bet J.K. Rowling and Dan Brown have great fun with this!
All this is part of a greater trend to provide information for authors to improve their own sales and perhaps target new markets. I'm sure that it will also help advertisers to target ads better. I like seeing tools like this as I can check for myself how my book is doing rather than relying on other courses. The book sells for $30 on Amazon.com, this means that it has made $1,521 through Amazon. I have not yet received any royalties - must check that one up!