GS beat me to it. While I keep some favorite actual books and recycle paperbacks, I have gone the way of the Nook and Kindle for the most part. I truly wish that digital options had been around when I was in school, as paying $50-$75 for a required course book only to find that a new edition was coming out so I could not sell it back was no fun (for anyone else who got stuck with 'The Munz', I feel your pain).
That said, sometimes you need actual books. As has been mentioned, shelves aren't the way to go. Milk crates or a cabinet are the best options. Just be sure that both the contents and their containers are secure, as the last thing you want in an accident is debris flying inside of your van.