You have a book coming out soon. You're the kind of person who wants to know HOW it's doing: Is it selling? Is it languishing? Is it breaking records? You don't want to wait for the royalty statements, which take forever due to the lagging reporting periods. Well, there is some reprieve. There are a few places you can track your sales. You can even track your fellow authors' sales, and while this can be a boost to your ego, it can also be addictive and virtually like letting someone slap you every time you turn on the computer. Don't say I didn't warn you:
Bookscan ~ Members of RWA can go to rwanational.org, click on Bookscan, and select the $52/year option. You can log on weekly for a report of the 100 top selling romances. Not just a list of titles, but how many copies they sold this week, last week, and year-to-date. Research Bookscan to see what outlets are reporting currently, as it's not all markets.
On-line Bookstores ~ Amazon and other on-line bookstores provide a sales rank so you can watch how your book is selling in comparison to other titles at a moment in time. It's all relative, and it's listed on the same page as your title, right under the book's shipping weight. If you think this kind of information is interesting, see Publishers Marketplace.
Publisher's Marketplace ~ If you pay to join Publisher's Lunch, they provide a book tracker. With it, you can track your sales at amazon and Barnes & Noble. Hour by hour, day by day. You can also track fellow authors' individual titles.
Your Editor ~ Depending on the publisher you write for, your editor can provide a print run number before your book's release, then a sell-through percentage a few months afterward. So if they print 100,000 copies and your sell-through is 50%, you've sold 50,000 copies at the time she accesses the information. Harlequin/Silhouette probably still refuses to do this. Other publishers will. The further out after the release date, more returns have found their way back, and the more reliable the information.
That said, of course the only definitive, black-and-white, take-it-to-the-bank sales results are what you get when the second or third royalty statement finally arrives.