By moving individual atoms around, we can improve just about everything - from designing stronger, lighter materials to smaller computing chips to more effective drugs to toxin-eating nanomachines to other things we haven't begun to imagine.
But that's exactly the problem. We haven't imagined enough of the implications of nanotechnology, both good and bad. And when you're talking about manipulating things on the atomic scale, things can get very bad. Just ask Robert Oppenheimer - see what he had to say on the left.
Oppenheimer's quote: Now I am become Death, the destroyer of worlds. - quoting Hindu scripture upon witnessing the first atomic explosion.
This is from the Nanoethics Group based in Santa Barbara. Their approach to looking at the good and bad of nanotech seems promising