WARNING: If you cannot bear the thought of ripping apart an old book, no matter how outdated, useless, or dilapidated it is, stop reading now!
What to do with old hardbacks that one couldn't in good conscience even give to Goodwill? (Who would buy a college psych book 5 editions out of date, anyway?)
Answer: cut the covers off and use them for crafting fabric-covered boxes. The covers are extremely sturdy and make a perfect bottom. If you have appropriately-sized books, you can make the sides too, Otherwise use cereal boxes or something similar.
Permabound paperbacks + greeting card + plaid fabric...
Falling-apart astronomy book + old science textbook (en Espanol) + cardboard box + rainbow fabric...