I saw that TNG episode a few months ago when I was re-watching the series! I was amazed that they would do something like that in the 80s, but Star Trek was always ahead of it's time (1st interacial kiss & all).
I'm a fan of Japanese animation, and was always drawn to the gender-bending shows like Ranma-1/2, where a teenage boy is 'cursed' to change into a girl when doused with cold water (hot water changes him back). I thought about how great that would be, but then realized I'd be avoiding hot water!