The Da Vinci Code question

Is "The Da Vinci Code" the type of book you would use long tail marketing for ?

No, the long tail marketing is not based on books such as "The Da Vinci Code". "Da Vinci Code" is what we call a best-seller so its popularity is based on the lowest common denominator that enables to touch the largest people. Therefore, it does not need long tail businesses. But anyway, it will be probably in the products proposed in these types of business. The latter propose large ranges of fringe or niche products in order to touch the largest number of people. So applied to cultural products, it enables to find specialized products rather than common or popular ones.