(Image: William Liddiard via Gizmodo)
Inventor William Liddiard names them after himself, calling them Liddiard Wheels. They can attach to any car. In this case, it's Liddiard's own Toyota Echo. The tires roll horizontally, moving the car sideways. He writes:
Unlike other omni capable wheels, my wheels do not require the vehicle to be built around them. This is a world first bolt-on application for anything with wheels. Designed to be used in all weather and road conditions. They are stronger, faster, and more accurately controlled than prior art. They can take a beating. The tires can have the same build characteristics (siping, grooves, rubber compounds etc.) as regular tires. Now you can drive in all directions, and turn on the spot, when needed.
It's the perfect solution to parallel parking challenges.