A retrospective look at the ideas that mattered in the last 12 months.

What better time than late December to pause for a retrospective look at the ideas that mattered over the past year? In this era of specialization, no one person is qualified to offer a definitive list of this kind. So think of what follows as a proposition to ponder: all that follows is either going to reshape our world, or would reshape it if only the idea in question were given its due. Take to the comments section to offer ideas that ought to appear on lists like this one.