A few years ago I worked on applications for nanotubes. How about lightweight armor for Humvees? In fact, you can have invisible shields in front of your firing position (you know where the firing port is so you can still fire). Absorbs microwaves? Stealth tech. You can make a display with resolution so high you have a hard time telling it from reality (Holodeck). And, yes, a space elevator will now be feasible. I told my NASA friends that nanotubes would be the next big breakthrough. We've had them in the lab for years. We just needed manufacturing tech to make the applications feasible.
How 'bout incredibly LIGHTWEIGHT and strong automobiles? Gas mileage goes way up when your whole car only weighs 300 pounds.