Metamaterial lenses, if you can make them in visible-light frequencies, might be useful in the microlens array for light-field cameras, where they could act as

Metamaterial lenses, if you can make them in visible-light frequencies, might be useful in the microlens array for light-field cameras, where they could act as both the bayer color filter pattern and as focusing element, and where their excellent optical qualities would be really helpful. (The Lytro light-field camera's lousy optical performance is mostly due to the microlens array: they have to be made of conventional materials, and the only lenses that would fit are singlets, which have chromatic abbertation and barrel distortion out the ass.) But as the primary light gathering element, no.