4. Drones: We probably shouldn't have made that last upgrade.
Robots or machines designed to fight wars on our behalf could eventually turn on us. Most people don't seem too concerned about it given the popularity of consumer drones among hobbyists, but don't confuse a flying camera with a weapon of war. We continuously put more intelligence and more ammo into autonomous weapons that, frankly, were smarter and more powerful than us to begin with.
Should these artificial assassins get fed up with our drama–and they will—you may want to stock up on batteries and oil to appease our new robot overlords. Also, you could try turning it off and on again.
© VICTOR HABBICK VISIONS/Science Photo Library/Corbis