Creative thinking during an economic downturn will allow an entrepreneur to thrive while more-established companies founder, says British tycoon Richard Branson. Case in point: Virgin Atlantic, the airline he founded in 1984. It grew stronger as big airlines went bankrupt in the early 1990s. "There are enormous opportunities when there is a crisis," he says. "In a situation like this, it's absolutely essential to conserve cash." But don't let it sit unproductively, he says. Invest and expand.