Quite a lot of the stuff that has been written is not currently under copyright (see the very existence of Project Gutenberg, for example) and some stuff is just copyleft as a matter of principle.
If you were recommending books from that set (the set of things that are not under copyright) what would you recommend? What children's books, what fantasy or scifi or romance, or adventure, or [insert genre here]?
For that matter, are there any that stand out to you as the worst? I remember hearing somewhere about a writer's circle that had a copies of what they considers to be the worlds worst books, and they had regular contests to see who could do a reading for the longest while keeping a straight face and not breaking down laughing.