Every time you use a cell phone or log on to a computer, you could be contributing to the death toll in the bloodiest, most violent region in the world: the eastern Congo. Rich in "conflict minerals"--valuable resources mined in the midst of armed conflict and egregious human rights abuses--this remote and lawless land is home to deposits of gold and diamonds as well as coltan, tin, and tungsten, all critical to cell phones, computers, and other popular...