For those of us who relied on the hidden "advanced search" feature -- the great one that almost nobody knew about -- at Amazon.com to do book research, it's over. Amazon switched to an idiot-proof advanced search that only allows you to select from drop-down categories. Gone are the glories of typing in complex statements (subject: "political theory" NOT science AND title: energy AND publisher: "university press"). Basically -- for my purposes -- Amazon is now a little better than useless.
UPDATE December 18, 2007. I'm thrilled to report that Barnes & Noble does a much better search job, far more flexible than the new Amazon interface. It's still not possible to do the more complex searches that made Amazon so helpful before, but at least you can drill down to a sufficiently narrow category to do some serious book research. For example, if I need all the foreign affairs titles on North and South Korea, Amazon forces searches to start with all nonfiction, and then will only let you get to a certain level of detail before it insists on a keyword search to pick out the Korea titles. Given that just about EVERY foreign affairs book these days has Korea somewhere in the text, that's pretty much useless.
Barnes & Noble, however, groups things as follows:
Level 1: Politics & Government
Level 2: International Politics
Level 3: Asia - Politics & Government
Level 4: North & South Korea - Politics & Government
Much, much better. For those of us who spend much of our days researching comparison titles for books to propose to agents and editors, this is by far the better tool.