We've discussed using mirrors in unconventional ways, but this tops the cool list. There's the philosophical aspect of seeing yourself look back at you while you look at the piece of art, the creative surprise— picture on mirror? genuis!— and the functional double whammy of getting to use art and light-maximizing mirrors in one fell swoop.
This lovely idea hails from Frank Stuve's highly celebrated Berlin-Charlottenburg apartment, featured on Freunde von Freunden. I've seen framed art suspended on top of a framed mirror before, but actually using a mirror as a picture mat?— new to me!
It's possible that the photos are actually printed on the mirrors, but a similar look could be achieved by mounting the photographs on top of the mirror, and then placing the combination behind glass and a picture frame. That way, you get the reflection from the glass on top of the picture as well as the reflection from the mirror surrounding the picture.
Images: Freunde von Freunden