There is actually a company that does this. But since Amazon doesn't do OAuth, they require you to give them your amazon login and password. They download your

There is actually a company that does this. But since Amazon doesn't do OAuth, they require you to give them your amazon login and password. They download your account usage logs from amazon and put a GUI over it. The password requirement was a showstopper for me so I didn't even try the co. The graphs sure looked pretty. :) Sorry, the name of the company escapes me ATM.