A very good article here about the fortunes been made by Amazon Ebay etc by exploiting the long tail of consumer demand that is all those people whose purchases are not in the top 100. That is the cumulative effect of thousands buying many individual items such as back catalogue music and out of print books. Interestingly how Amazons software can pick out books that you may like based on past purchases and how the reviews help. Certainly true for me
Thanks Ole Eichorn for the link on his Critical Section Blog.
Another link from John Battelle on the idea of the profit in the tail here