After Amazon ( AMZN ) CEO Jeff Bezos unveiled a futuristic drone -- designed to fly packages directly to your doorstep in 30 minutes -- the reaction was swift and furious on social media. Just a day after the research project, known as Amazon PrimeAir , was unveiled on CBS' ( CBS ) " 60 Minutes ," Twitter ( TWTR ) was full of drone chatter.

Comments ranged from "creepy" to "Just for the record, I'm 100 percent not on board with Amazon flying my packages in on drones like they're my sponsor in the (expletive) 'Hunger Games,'" said another tweeter. A common reaction: What the heck!?

But for all the passion, suspicion and ethical questions about unmanned aircraft and privacy, researchers have been working with drones in many fields -- beyond retail -- for years. Consumers already have been exposed to the iRobot ( IRBT ) vacuum cleaner. A more serious application has been unmanned aircraft used in modern warfare.

Now with the U.S. national airspace opening to unmanned aircraft by 2015, many small- to mid-sized manufacturers are preparing for more nonmilitary customers. They're creating smaller, affordable models for surveillance and public-safety use.

Click ahead to explore emerging trends in drones, robotic warfare and beyond. "We're just scratching the surface of this," P.W. Singer, author of " Wired for War: The Robotics Revolution and Conflict in the 21st Century ," told CNBC last year.

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