I would have said something like Google Glass, but we have seen the social flaws in that approach.

Barring that, smartphone apps seem like the obvious runner-up. A smartphone-centric personal assistant which helps people make better life choices would be a gimme.

Alternatively, a distributed TaskRabbit-like application where AI anticipates people's needs and points potential helpers at them could tremendously benefit society.

That might be a less glamorous interface than cybernetic implants, but it's achievable with what we have now.