Until very late in the piece if you logged in all-caps it flipped your terminal session over to an all caps login assuming you were on an ASR33 teletype. I think it dropped out after BSD4.3 -I did actually use this state.

Nobody I know in my cohort/age-group thinks capital letters make a different command. Lots of us inherited a memetic state of alias/function to make a single "l" do some variant of the ls command. And "m" for more was not uncommon. "p" to pass to the large for some, never bothered me much to type more letters.

Other than that, the "w" and . Are about it. . As an execution invitation feels less like a command than just syntactic suger.

(As does the cryptic :> to zero instantiate a file)