First of all, when you first go into the books store [on Barnes & Noble's Web site] and look at the side for the categories (which I see as looking for book shelves) and choose Fiction, you are given 4 choices versus 19 for Amazon’s Fiction listings. Say you are interested in historical fiction–there is nothing for you. So then you look at the stuff in the center of the page–and you get the equivalent of the tables at the front of a bookstore (you know, best sellers, new releases, editors picks)....
[She eventually finds historical fiction, but it takes forever and she's not sure she could do it again.] As the author of an historical mystery, I know that these odd byzantine browsing paths help explain why I sell so few books on Barnes and Noble, while other authors (who are in one of the main 4 categories or instant collections) are selling well. The readers just aren’t finding my books.
Floor placement is incredibly important to brick-and-mortar retail. It's why a company like Coca-Cola will pay extra to have their product placed on the eye-level shelves or (even more expensive) stacked up at the end of the aisle of the grocery store. It's why when you go into a department store, the first floor is cosmetics and handbags--those have a higher profit margin than the actual clothing you have to go up three floors to try on. And it's interesting to see that floor placement is every bit as important in a virtual store.
I've seen theories that Barnes & Noble just attracts a different audience than Amazon--and I'm willing to believe that they do to some degree, because different brands typically appeal to different demographics. But clearly one piece of Amazon's success in selling indie authors (and they are very successful at it--a large majority of indie writers make the large majority of their sales on Amazon) is their virtual floor plan. If you highlight only the best sellers, then that's pretty much all you'll sell. If you make it easy to find weird and obscure titles from people no one has ever heard of, then you'll sell those, too.
(And yes, the post she left the comment to is the result of a tip from me, because I knew Passive Guy would be interested in the subject. But her post is actually on another topic, so I don't think we're too far down the rabbit hole here....)