Wow. Amazon makes the text of the books in it's database searchable.
Geeks, forget the technicals for a second. This is brilliant strategy.
It's
killer features like this that give Amazon a total lock-in on this market - Google does the same thing. In both cases, they're providing additional benefits to consumers, raising their switching costs.
This is part of a larger strategic intent -
learn from your user base, and give them what they'll
value. This may sound really dumb, but think of how many
entire industries can't seem to think this way - and abuse their consumer base (and are thus in a lot of trouble): music, food, finance...