Not to mention that it is quite easy to carry around a library of several thousand books. All instantly accessible, not taking up any space other than that of the Jetbook. Not sure about your wife, but mine hated the piles of paper books scattered around my favorite reading chair.
Ken is quite correct about the many different sites where free books can be found. As is Russell on the monetary benefits of owning a Jetbook.
I soon found that my biggest problem was that my wife was incredibly jealous of my ebook reader. Of course that problem really isn't that hard to solve.