Nonfiction in Fiction

No matter what setting a story is in, there are always elements of nonfiction in them. There need to be in order for people to understand what's going on. Lord of the Rings may have orcs, dwarves, and elves (which are all still humanoid sentient beings), but it also has swords, bows and arrows, castles, horses, boats, and most importantly, second breakfast.

What I find interesting are stories that take some existing concept/technology and take it to its next logical advancement (Michael Crichton), place it in the context of a completely different setting (Terry Pratchett), or have a story take place during monumental historical events (Count of Monte Cristo). Each of these raise different questions for me that I enjoy trying to answer. What would happen if cloning became cheap and freely available? How did people decide what signal meant what using semaphores? Did history actually take place like that (History was my least favorite class in school...)?

I think the sign of a good author is one who does his research and makes the uninformed or semi-informed people doubt what they know or think things could happen the way they do in the story. This should also apply to other forms of media, but I can't really think of any movies, TV shows, or video games that made me really ask these questions. Some even make it very clear they don't understand anything about what they are portraying.

So what are your favorite extrapolations of existing technology? What is your favorite story that takes place in history (but doesn't necessarily affect/alter that history)?