There's a powerful sci fi short story I read in an anthology quite a while ago (I believe called The Flying Dutchman) describing a crewless bomber being repaired, fueled, taking off, bombing its target, landing, and then doing the same thing again. As it describes this repetition, you slowly realize that humanity has long since been wiped out and the bombing runs are automated systems repeating themselves. (That's my memory of the story, anyhow, I read it in the 80's :) ).

(Edit: found it, "Flying Dutchman" by Ward Moore, it's from the 50's and you can find its text online with those terms)