Sure the unmanned aerial vehicles can be used to rain down hellfire on terrorists overseas or surveil our borders to prevent
undocumented illegal immigration. But I'm pretty sure that this is the real reason they were invented:
During August's OppiKoppi Music Festival [in South Africa], attendees can order beers from their phones to be delivered the event's District 9 campsite. The beer-equipped drones will swoop down and deliver beer via parachute to the appropriate customer, as explained in the video above. The organizers say the beer drones are now hand-guided, but in the future they'll fly on a GPS grid.