Bookshelves are a wonderful thing.
Kate and I have been living without enough book space since we moved in together - all our shelves have been double-stacked. Finding anything is a pain, because it's impossible to tell if you still own the book you're looking for.
No longer. One short visit to Ikea (plus delivery and assembly), and we have a huge 5x5 Expedit bookshelf dividing our living area. It has comfortably absorbed our entire collection (plus boxes) - we have double-stacked it, but can access both sides. Books are grouped by subject matter, so can actually be found. (We have a huge O'Reilly collection, but gave up sorting by publisher when we discovered various non-computing books in there...)Now I can sit on the sofa, and have (paper) reading material within arm's reach. It's good to have something more to our living space than a television and a pair of laptops. As an added bonus, you can't see the washing up from the living room any more.