Quadrocopters: One very likely future for all sorts of autonomous flying vehicles. New research  is even showing how these 'bots can cluster together in swarms to lift anything from human-sized upwards. Sci-fi never seemed so real.
Advances in batteries and motor miniaturization enabled the craze of those mini indoors helicopters that've swept the world in recent years, and Quadrocopter research has made astonishing leaps and bounds in what a small autonomous flying vehicle  can do. Versions of these tiny unmanned air vehicle may be performing surveillance in combat situations soon, or even swooping into burning buildings or disaster zones to help look for survivors. But that's not all.
But did you ever imagine that these things could swarm together, in a faintly Matrix-esque way, to turn into a clustered flying vehicle? Scientists at ETH Zurich's Institute of Dynamic Systems and Control did, and they've been building flying robots that can physically dock with each other to experiment with the idea. Each helicopter in the "Distributed Flight Array" is a separate vehicle with its own motor, sensors and flight control systems. But they can locate and connect up with other vehicles, and then fly en masse.
A cluster of vehicles is capable of hauling much more mass into the air than a lone 'copter. And with enough all hooked together, there's almost no imaginable limit to what these little guys could lift into the sky as cargo. The cluster even allows for the safe failure of one or several individual aircraft, as the others can take up the slack--or even maneuver to allow the "dead" ones to be replaced mid-flight.
This is just a research project at the moment, but with the right kind of success and heavy-duty production models, quadrocopter cluster robots may turn into an incredibly useful tool.
Also have a look at the video from a different team at ETH Zurich (as seen on BotJunkie.com ) who've been working on precision control and flight of quadrocopters. They've achieved such accuracy that they can make a pair of these craft perform an airborne ballet. That's right, these things can dance.