Available here, but only in pre-made Chinese designs:
If you could get an entryway mirror that was a magic mirror, you could point and area light at it and has an image of your house-hold members appear on the floor or opposite wall.
Or do a puzzle where you need to reflect a beam of light off of multiple mirrors in a specific order to get the image.
Or just make a cheesy action film starting with, "the map is in the mirror".
Pretty nifty, if you ask me...