In the wake of President Robert Mugabe’s re-election in July, some speculated about a return to the Zimbabwe dollar, which collapsed in 2008 under the weight of hyperinflation. Two tech gurus ponder innovations that might emerge if such dark times returned. Perhaps a smartphone app that works out what to charge in the afternoon based on prices in the morning. Or one that uses GPS technology to direct motorists to petrol stations that have not yet run out of fuel.  Entrepreneurs in Zimbabwe from the Economist.