The spike, the HUGE spike, in sales of Orwell's 1984 since the NSA story broke was detailed on Amazon's Movers and Shakers page. If you want to see how something is selling, Amazon is more than happy to give you the details. In IT this is referred to as "analytics," because IT people think it sounds cooler than "statistics" or just plain "sales figures."
The point however, is that it is sometimes fun to see what other people are buying versus what they recommend. The M&S page lists by percentage gain, so something ranked 80th in overall sales (like 1984) might show below something ranked 231. It gets confusing but it's fun to check out anyway. Since the book lookup feature on Booklikes uses the Amazon database, this seemed relevant to pass along.