In the last 20 years stained concrete has grown remarkably in popularity as a residential flooring. It is quite durable and versatile and can come in a wide range of colors and finishes. The floor can also be scored (decorative lines cut into the surface) to provide interesting design features, as can be seen in several of the photos below. Stained concrete can be done on an interior of exterior basis and can even be used on vertical surfaces.
The picture immediately below shows a concrete and wood floor.