OK, so, the nose twitch is iconic to Samantha and the blink is iconic to Jeannie.... But with Jeannie, ALL the genies blinked to do magic, her sister, mother, even the male genies did I THINK.... But with Samantha it seems she is the ONLY one to twitch her nose.... Did any other witch on the show EVER nose twitch to do magic...Serena, or any others? I know Tabitha did but did anyone else?

It seems it was Samantha's trademark, to twitch her nose. Of course, Tabitha had to use her finger to twitch her nose, and would also cross both of her fingers in later seasons. I only remember Endora doing the hand flourish, and Serena always snapped her fingers. Poor Aunt Clara would always mess up her incantations and she did the hand flourish as well. The same for Esmeralda too, I believe.

Twitching your nose without also moving your mouth is not an easy thing to do. Most people can't do it. The sound effect was what made it memorable.