Just as the spreadsheet programs of a generation ago revolutionized business planning, so today's simulation programs offer tremendous potential for better decision-making, more accurate resource allocation, and superior business forecasting. This article overviews recent developments in simulation programs, and offers guidelines for choosing among them. Most simulation programs use algorithms to manipulate data, and can display the results of specific queries as single interactive flow charts. These charts can be used as training aids that enable managers to work through hypothetical situations and test proposed solutions to various problems. Simulation programs have been used successfully for airline passenger routing, cargo handling, and electric utility power routing, to name but a few applications. Simulation programs are beginning to be run in parallel with the actual operations of organizations, enabling planning to be done with real-time data.