One thing that infuriated me when I got into photography was that there was no standardization on which direction twisty-focus lenses should focus. Some people just don't seem to care, but I personally think it's a big deal.
All civilized cameras, including Leicas, focus to infinity by turning the lens clockwise (when viewed from the front) as God intended. Some cameras, on the other hand, focus toward infinity by turning the lens counter-clockwise (imagine!). I even have some 3rd party lenses for my Pentax cameras that focus different directions from the Pentax lenses!
Every now and then, I read about some camera system on the internet and wonder which way it focuses. For example, do Hasselblads focus properly like a Leica or are they backward like Nikons? It makes a difference to me. So, I think it would be good to list them for reference. I will start.
Leica M--clockwise to infinity
Olympus OM--clockwise to infinity
Canonet--clockwise to infinity
Mamiya 645--clockwise to infinity
Pentax--counter-clockwise to infinity
Nikon--counter-clockwise to infinity