I've found no recycling effort more satisfying than sweeping all my never-to-be-read-again paperbacks off the shelf and into the hands of our servicemen around the world.
"Hurry up and wait' is a cardinal mantra of the military, and we all know how tedious waiting around -- or being hospitalized -- can be. Reading is a powerful antidote to such boredom.
There must be literally millions of used paperbacks gathering dust on bookshelves around the country, and I urge you to give yours a new life; especially in such a rewarding way.
Just link to http://www.operationpaperback.org/. They'll give you detailed, step-by-step instructions on how to go about it.