Here's a stat worth knowing: In the UK, 63% of men who finish short-term prison sentences are back inside within a year for another crime. Helping them stay outside involves job training, classes, therapy. And it would pay off handsomely -- but the government can't find the funds. Toby Eccles shares an imaginative idea for how to change that: the Social Impact Bond. It's an unusual bond that helps fund initiatives with a social goal through private money -- with the government paying back the investors (with interest) if the initiatives work.