Imagine a triple-decker plane that could carry 800 passengers, made almost no noise, and generated much of its own power in flight. Barcelona designer Oscar Vinals is working on that vision, and while much of it depends on whether technologies just starting to be developed work out as well as hoped, many aspects of it could become part of more conventional planes.
Some parts of the plan for the plane, dubbed "Progress Eagle" are developments from existing technology such as winglets; others have been proposed by others, such as making the plane lighter and sleeker by replacing windows with large LCD images, and some seem unique, such as generating power by on-board solar panels and a wind turbine. And some depend on learning to use new materials more efficiently.
And even if you're skeptical about the whole project, Vinal's project website has a lot more detail, and some of the coolest artist's conceptions ever, as above!