Inventions. My top runners in the area of physical inventions would have to be ways of harnessing energy, ways of moving around the world, and ways of communicating. And since the latter two depend on the first, I'd have to put my money on energy control and use.
But we've got lots of psychological and social inventions as well. I'd put the idea that all people are equal at the top of the list. This is an invention that we could make better use of.
Links:
[1] http://edge.org/annual-question/what-is-the-most-important-invention-in-the-past-two-thousand-years
[2] http://edge.org/inthenews/what-is-the-most-important-invention-in-the-past-two-thousand-years
[3] http://edge.org/contributors/what-is-the-most-important-invention-in-the-past-two-thousand-years
[4] http://edge.org/responses/what-is-the-most-important-invention-in-the-past-two-thousand-years
[5] http://edge.org/print/response-detail/11883
[6] http://edge.org/memberbio/joseph_ledoux
