Google is working on a technology that, if perfected, would prevent about 35,000 deaths per year in the United States and 1.2 million deaths per year worldwide. To put that number in context: About 23,000 American men and women will die of leukemia in 2012, according to the National Cancer Institute. But while the technology Google is working on isn't the cure for cancer, it's pretty impressive. What is it? Self-driving cars. According to the U.S. census, 33,808 people died in car crashes in the U.S. in 2009 — 37,423 in 2008. According to the World Health Organization, 1.2 million...