I've gotten rid of a lot of books using PaperBackSwap.com. Yes, some books are simply out of date and won't move. And as my interests change, the first place I go to request a book is Paperbackswap.com. If nobody wants the books I've listed on PaperBackSwap.com, I leave them posted for 1 year, then they go to the Public Library's book sale. They take any and all. Your local library may have guidelines on when you can donate and how many you can donate at a time so it is wise to check with them. I have been very surprised at what books are requested of me through PaperBackSwap.com; some that I thought nobody would want do go to someone else. There are people who still do want books!