Wired has just published an article called The Long Tail. It discusses the so called "shallow end" of the market, and predicts that from now on niche markets will start to dominate.
The article opens by discussing how the publication of Into Thin Air almost a decade after Touching the Void led to the earlier, almost forgotten, book entering the New York Times best seller list. Eventually it overtook the newer book in sales, almost entirely based on it's Amazon recommendations. It's an interesting article, although some of the author's conclusions are, perhaps, a bit on the shallow side.