Hal Varian has an interesting piece in today's NYT about Amazon and the impact of used book sales on new book sales. He concludes that "all in all, it looks like the used book market creates a lot more value than it destroys."

Moreover, the presence of lower-priced books on the Amazon Web site, Mr. Bezos has noted, may lead customers to "visit our site more frequently, which in turn leads to higher sales of new books." The data appear to support Mr. Bezos on this point. [Reading Between the Lines of Used Book Sales - New York Times]

I wonder what the impact of putting a find-in-a-library button on Amazon would be?