A few years back I came across an article in one of the many magazines that many of us subscribe to. There was a small article that described using a cell phone instead of a mirror to check an unknown corner or area.
This tip certainly shouldn’t be used in place of good tactics (metering displacing, for example), but it can help. Since many of us no longer carry pocket mirrors, but do carry cell phones that have cameras in them try it out. Turn on your camera and stick the lens around a corner. You can watch your screen as you “mirror” your corner. Try it out at home, and you will be amazed at what an easy way this is to keep your head around the corner. If your phone has a light on it, that can help also, but the phone alone is pretty good even in low-light.
Throw it in your tool box and be safe brothers and sisters.