Here is a picture of the kind you do not see very often in economics:
What it shows is the pattern of specialization of different parts of the world, and how different commodities are related to each other in product space according to a particular metric of proximity.
The work in question is a collaboration between my friend and colleague Ricardo Hausmann and the well-known physicist Albert-Laszlo Barabasi, along with two graduate students (Cesar Hidalgo and Bailey Klinger), and has just been published in Science magazine. You can download it here.
How does this framework help us think about development and specialization? As Ricardo would say, think of the product space as a forest, goods as trees, and entrepreneurs as monkeys. Countries develop as monkeys jump from tree to tree. Trees further away are harder to jump to. Some parts of the forest are denser than others. What trees you have monkeys on today determines where your monkeys will be tomorrow. And it goes from there.