The long tail
Have you heard of the long tail? Chris Anderson coined this term in 2004 and wrote an article about it in Wired magazine.
There's even a blog about it.
The concept is that in the past, due to distribution and geographical constraints, retailers could only carry products of high popularity. Where a Barnes and Noble retail outlet can only stock their 40,000 best selling books, Amazon.com can make more money off of all the other books they have for sale than they do off their top 40,000 books. That is the long tail.
I find the concept and how our world is changing to be fascinating. If you haven't heard of it, check out the links above.