Nicholas Carr
makes the case for bundling physical books with ebooks:
Bundling a free electronic copy with a physical product would have a much bigger impact in the book business than in the music business. After all, in order to play vinyl you have to buy a turntable, and most people aren't going to do that. So vinyl may be a bright spot for record companies, but it's not likely to become an enormous bright spot. The only technology you need to read a print book is the eyes you were born with, and print continues, for the moment, to be the leading format for books. If you start giving away downloads with print copies, you shake things up in a pretty big way.