I wonder why the books are all non-fiction. I could imagine it would be entertaining to chat with large works of fiction.
I'd be interested in more fiction too.
Hmmm... Lord of The Rings would be very interesting, for having uses more like "non-fiction" too, people interested in finding various "facts" from it's universe. Or how about not just LOTR, but put in all the works of relevant Tolkien: Hobbit, LOTR, Silmarillion, etc, in the same GPT. Wow, people would actually be pretty crazy for that.