I've always enjoyed biographies of writers and scientists (eg: Isaac Asimov, Thomas Edison).

I think Dickens wrote a lot of non-fiction essays. I seem to remember reading about his travels in america; a short story or short book, can't even remember the title right now, but it was very amusing.
My ds8 isn't really drawn to non-fiction so I figure we might need some of these ideas in future. Good thread!