The Long Tail: How Endless Choice Is Creating Unlimited Demand by Chris Anderson

Passionate, crisp writing about how the Internet creates (and supplies) unlimited demand. 
The Long Tail of online consumer demand and products breaks through the barrier of physical space that bricks-and-mortar retail requires and allows innovative models of supply. It is described with several case studies and some very accessible data analysis.
By now a classic, the book sparkles as it lays out the ground, presents the arguments and the first few case studies. Reading the latter half, where case study is piled on case study, I found my attention lagging.
Must-read, if you want to understand the economy of the Internet