For those of you who would like to get a better look at how Amazon.com works in between the top 100 and the bottom millions, check out the discussion of the long tail at Amazon at http://longtail.typepad.com/ the_long_tail/2005/08/a_methodology_f.html.
It is a long discussion, some back and forth, with a bunch of technical details and numbers, but it really shows the unpredictability of Amazon.com, especially in the 1,000 to 100,000 range of sales rank.
