I'm not currently culling books, having done a big edit before relocating 4 years ago, and a mini cull (mostly DH's work library) 6 months ago, but I wanted to point out that libraries will often accept books of all sorts. Good quality hard cover books get integrated into their collections, and other books get sold during fundraiser book sales. Our seniors center also has a wall of shelves and books (mostly paperback) for 'take one/leave one' and some clubs will absorb books (my quilting group took all my books AND magazine collection on the subject. They also took my excess fabric stash for community quilt making projects.)

If you are doing a household edit, and books are up for review, consider a donation to your local library.