As a buyer,

– Good reviews and info about the books.
In a physical bookshop, you can pick up a book, read the blurb on the inside of the jacket. So I like a similar thing on the web.

- Nice pictures. For those of us who do judge a book by its cover.

- Thoughtful navigation. Again like a real bookshop, sometimes you want to walk in a say, have you got such and such a book, then buy it and leave. Other times you feel like browsing to find something interesting. Then even over times, there might be a reading or speech or event. (The online equivelent would be feature articles, reviews or interviews with authors)

I just thought of a neat idea. I’d like to have a place where I can manage my personal library, like a personal page, where I can list the books I already own, even write reviews of them, that other people can read. And a wish list, where I can keep a record of books I’d like to get.. (I always read reviews of books, and think, gee I must get that some day, then forget a week later.)
You know its the latest thing, ‘Peer Content’ where you get your customers to contribute to the content of the site. So a bit of a bookworm community feeling about it.. Even the sellers can have their own page, even blogs..

But even with all that stuff, still easy navigation, so you can just pop on, see if there’s the book you want, and buy it.