Without it all of our computers, telecommunications, vehicles, aircraft etc. are slow, or significantly less efficient. It allows us to transmit data through the air or glass cable rather than clunky copper. Yes, the pill is significant, but there are other methods of contraception, and war, disease and famine take care of a lot of the other problems overpopulation can cause. The horse-drawn plough. The horse enabled people to become mobile, wage wars, seek better lands, and hunt over a wider area.
Civilization owes much to the horse.
Definitely the printing press. The first means of mass communication. Though I'm still not completely clear on rayfo's intended direction for this discussion, I suspect we are still travelling away from the point. I think the best invention in the last 2000 years would have to gunpowder. It has paved the way to epic wars and space travel.