People are always talking about the amazing predictive abilities of science fiction. But what about fantasy?
Yes, yes, Arthur C. Clarke, communications satellites, yadda yadda. Beat this, Sir Arthur:
. . . till at last each sheet was a splendid map of the Eastern Ocean, showing [various islands], all exactly the right sizes and in the right positions. They were the first maps ever made of those seas and better than any that have been made since without magic. For on these, though the town and mountains looked at first just as they would on an ordinary map, when the Magician lent them a magnifying glass you saw that they were perfect little pictures of the real things, so that you could see the very castle [...] and streets in Narrowhaven, all very clear though very distant, like things seen through the wrong end of a telescope.
--The Voyage of the Dawn Treader, by C. S. Lewis, p. 187 of the 1994 Harper Trophy paperback edition
(Note to those who don't know me: the snide tone of this entry is, of course, tongue-in-cheek.)
Other examples of remarkably precognitive fantasy writing welcome. Try to avoid arguments about what's fantasy and what's not, though I realize this topic will inevitably lead to that one.