True Flight's navaid database stores the fuel prices of over 3,000 FBO's, updating approximately 2,600 prices every month.  On a typical trip it is not unusual to save 75 cents -$1.00 per gallon, often by refueling at an airport you would of never thought of checking!  The Flight Cheetah cycles through  hundreds of airports along your route to quickly show you in order of cheapest to most expensive allowing you to select what is best, given your route of flight and current weather.