Why is it that when people dip their fingers into the wine after havdalah, they use their pinkies? Why not their pointer?
While this seems to be the common custom, in fact some have the custom to use other fingers, see Siddur Beis Aharon pg. 3 who writes to use the ring finger. I have not seen an explanation for the pinky finger. This custom is meant as a healing method for what the Talmud tells us that one loses some of their eyesight due to walking in a haughty fashion. Perhaps we use the smallest finger to remind us of the trait of humility which we are trying to return to with this wine.
See Berachos 43b, Prisha O:C 269:3, Pri Megadim, Eishel Avraham O:C 301:1