I may be in a minority, but I was unaware of the 'nvram' command until I found this thread.
It seems very useful. I note from a quick search that 'nvram show' will list other NV parameters that can be set the same way. In fact I just tried 'nvram show', and it produces an extremely useful display of many settings, even including the wifi passphrase and the login password in plain text. Perfect for an old-fashioned archive, of the form that can be pinned to the wall with a drawing pin!
Sorry if everybody else already knew this, it was welcome news to me