> Offer the books to your local library. You can always visit them ;)

Incorrect. Donating is nearly the same as selling them. Libraries don't lend donated books (in the common case), they dump them to a resell wholesaler for pennies on the dollar.

But still, better to pass your book along to someone who might read it, then to have it collect dust.

Well, I suppose it's just a difference between countries. My books are definitively available at my local library.