My first car (a 1967 Dodge Monaco) had 'backwards' lug nuts on the left hand side of the car...

http://en.wikipedia.org/wiki/Lug_nut#History

Propane tanks also used to have backwards screwing connections. I believe this was a safety 'feature' given the mainstream use of small propane tanks. Having them tighten counter-clockwise prevents similar looking but wrong hoses from being attached to the tank. It also tricked people who didn't understand propane tanks form being able to remove a connection (since they would usually just tighten it further).