Year-round holiday christmas lights
I noticed more people putting up purple Christmas lights for halloween, red / white / blue lights for the 4th of July and even multi-colored ones for Thanksgiving. It'd be cool if a company manufactured year-round lights, LED's or fiber optics, that had different settings so they could be different colors.
Then, a person could set them to multi-color or red / green on Christmas, and leave them up until they can flip the switch for the next holiday.