Mirror screen for smartphones
A smartphone screen that is both highly reflective and can act as a good mirror, in addition to transferring light through the screen to display the actual user interface and allow it to be used as a normal smartphone. I am not yet sure whether this would be possible with today's technology, however, I think if it can be developed and put to market it would make a big difference in people's lives. I know that I sometimes use my phone screen as a mirror when I am in a rush and I didn't get time to adjust my appearance accordingly, and if only it were more reflective, it would make a great mirror.