It's a good bet that in the not-so-distant future aerial drones will be part of Americans' everyday lives, performing countless useful functions. A far cry from the killing machines whose missiles incinerate terrorists, these generally small, unmanned aircraft will help farmers more precisely apply water and pesticides to crops, saving money and reducing environmental impacts. They'll help police departments find missing people, reconstruct traffic accidents and act as lookouts for SWAT teams. They'll alert authorities to people stranded on rooftops by hurricanes and monitor evacuation flows.