Maybe, its late into the night and my eyes are getting droopy but I believe I found the first piece of information in photography that veers towards madness and unhealthy obsession in photo-taking - lens reversal.
Apart from the usual use of auto extension rings (e.g. PK-12/13) to further help lens like the Nikkor 50mm F/1.8D work more like a macro lens, I came across a lens reverse-mount kit from the old library of Nikon! People actually do that in hope that the non-centralized focal length be reversed closer to the subject. Most importantly, it works! Madness I would say, but genius to some others.
