There are all kinds of things like these that pop up regularly. The problem is moving it out of the laboratory and into the hands of consumers. How reliably does it work? How much money will it cost to produce? Things like these.
We have no problem storing and reading data down at an atomic scale. The densities around that are HUGE, but I don't think you're going to be seeing any electron microscopes hooked up to TVs to play movies stored on grains of salt any time soon.