Curious everyone seems to be leaning towards the internet stuff as the big shocker. I think more like electricity. Intercontinental air travel and motorized horseless carriages.
Despite all that, the social stuff is not as different as you might assume. I've read a few books written in that period and there's still a great deal of common ground to be found at the basic social level. Plant 1700's European man in a pub and he'll be right at home. ;)