There are some things in Star Trek that go on that would seem to have HUGE impact, but are suddenly never brought up again. Life changing technologies that are never realized, or characters who were just, let loose, into the Star Trek universe, never to be heard from again, or even a small element of a plot that the episode just brushed off as if nothing, but left you going "Hey what a second!" What story element like this has always left you saying "I would love to explore that more!"?