The University of Nebraska-Lincoln's NIMBUS lab recently received clearance from the FAA to begin outdoor testing of their firebombing UAVs, designed to aid in conservation and wildfire prevention efforts.
Here's how they work: these robotic drones each carry a payload of plastic spheres containing chemicals. Then, they inject a liquid into each sphere mid-air before dropping it into a target area. The chemical concoction causes a reaction that results in a burst of fire on the ground.
Although in the wrong pyromaniac's hands (OK, ours) this would be a seriously bad thing, this actually has great positive implications for setting controlled burns in a safer, more economical way than the current methods (by hand or helicopter).
Still: firebombing drones. Check out this video to see 'em in action:
Photos by University of Nebraska-Lincoln