Now here's another great idea from the MAKEZINE blog. Not only do you get more furniture for no additional cost, but you recycle without having to go through the tortures of wondering whether or not traditional recycling consumes more energy and materials than just creating new materials.
There seems to be many great ideas out there in cyberspace for re-birthing old library junk (including culls and weeds) for other purposes.
If you've got a spare moment or 30, check out the Instructables website. There's also information on the Inverted Book Shelf (see right), which would be a great gag for libraries on the next April Fool's Day. Mind you, to do this to a whole library is just asking for a whole lot of extra work, if not something a tad more serious in the disciplinary area.