Israeli energy company Innowattech has created a new type of road that generates electricity as cars drive on it:
The supercharged surface is embedded with piezoelectric crystals, which transform kinetic energy from passing vehicles into an electrical current. With widespread adoption, the technology could feed energy back into the nation’s burgeoning electric vehicle grid, transforming congested roadways into a clean green source of energy.
The amount of electricity produced isn't that much (400 kilowatts per kilometer or 645/mi), and there's no mention on how cost effective it would be. But given the sheer amount of roadways we have (the US has over 4 million miles of roads and streets in its highway system alone), it's an interesting albeit niche approach to generate electricity.