Books and tools are my two vices as well. Books especially -- there's something to be said for the user-interface both of an individual paper book, and of a wh

Books and tools are my two vices as well. Books especially -- there's something to be said for the user-interface both of an individual paper book, and of a whole bookshelf, in terms of ease of navigation. PDFs allow you to grep but spatial memory is much better suited to physical things. And I'm much more likely to pick up a paperback from my bookshelf when I'm looking for something to read than I am to go find a PDF and sit in front of my laptop/tablet. And finally I really like the social aspect of physical books. "Hey, we were just talking about X, and you might like this book!" works way better with paper than with a PDF.