At college I used to always feel that books should have a search feature like we have a search functionality in PCs. Amazon.com has come with this new feature which allows one to search inside the book(content of the book). It has one of the largest digital content archive. If I have to look about a particular word in a book then now I can do that.
I have this feeling now this could lead to plethora of other things basically it would cause a sort of disruption.