If you have a book (or some other thing that still has some use) that you don't want anymore, and you can't bring yourself to recycle it, you might consider Freecycle. I sent a patron to this site today, because we couldn't think of any libraries that would accept his 20 year old encyclopedia set.
Freecycle is a group of locals who post items that they would like to give away on an email listserv, and anyone who wants the item can reply to the email. Usually the winner is the first person who is willing to pick up the item. If you are concerned about giving out your home address, you could arrange a time and place to meet in public to hand over the stuff. People give away bicycles, mattresses, snowblowers, clothes, kitchen utensils, you name it.