Fibonacci numbers are also found in a branch of stock market analysis called Technical Analysis.
Fibonacci fans, arcs and retracements are often used to try to predict future stock movements. For example after a stock price has moved upwards (rallied) and starts to move in the opposite direction, a Fibonacci retracement can be used to try to determine the point at which the stock price will start to turn upwards again.
It very often works too, spooky really.