Space elevators. Once we get the tech working on those babies we'll really start making some progress in space. Once the infrastructure is up, the cost to orbit will be pennies on the dollar over anything else we can think of today. A vacation to an orbiting space hotel will be not much more expensive then a first class vacation today, and not any harder physically on the body then a conventional airliner flight. I am holding out hope yet of retiring to an old folks home up there.
