Congratulations, that's terrific!
Yes, watching your Amazon rankings can be terribly addicting. Since they're so temperamental (changing hourly), you might want to check out this website http://www.novelrank.com/track.php
(it's FREE) that allows you to track the sales on Amazon (both print and Kindle) of any book and converts your sales rankings into "estimated" copy sales. I've found their estimates to be pretty accurate, and once you start monitoring your book on the site, it keeps track of your sales rankings (and, again, estimated copy sales) over time, so you can begin to look back to see how it's gone up and down and try to figure out what things do/don't impact sales.
Also on Amazon via your author's page, there are now some pretty neat (and, again, FREE) features for tracking your estimated book sales (print only) in bookstores across the country using Bookscan data. It, too, is only an estimate, but I find it very useful (particularly the one tool where sales are shown on a map for different parts of the country) for judging the impact - or lack of impact! - for various promotional/media stuff I do, like local radio show in various markets across the country.
Congratulations again, and good luck!