When you've just finished reading the latest new novel, where does it end up? For most people, it's likely to land permanently on the shelf; a few dedicated readers might break it out for a second read later, and fewer still might lend it to a friend. Other than acting as a display of your good taste in literature, it might not ever be used again.
What if it was a little easier to donate a book after you were done? An Australian design firm worked with a publisher to start redesigning book covers: now, the dust jacket of some new novels in Australia can be flipped around, bent around the book, and sealed to be sent to a nonprofit that gives books to the homeless. The design is flexible, so it can easily be adapted for different book sizes and edited to include a different nonprofit's address in the region where the books are sold.