This story at Slate is sad and funny and interesting: It's about how the internet has turned used book buyers from a specialized kind of craftsman into automatons:
I make a living buying and selling used books. I browse the racks of thrift stores and library book sales using an electronic bar-code scanner. I push the button, a red laser hops about, and an LCD screen lights up with the resale values. It feels like being God in his own tiny recreational casino; my judgments are sure and simple, and I always win because I have foreknowledge of all bad bets. The software I use tells me the going price, on Amazon Marketplace, of the title I just scanned, along with the all-important sales rank, so I know the book's prospects immediately. I turn a profit every time.
If you've ever been to one of those Friends of the Library sales, you've seen these people, scanning through books with a beeping handheld device, without even looking at the titles. If there's a better physical representation of what the internet has done to bookselling, I sure can't think of it.