Historical clue formulations

• Travel aid in science fiction — 2022-06-11
• Dance in which "you bring your knees in tight" — 2011-03-25
• Dance in "The Rocky Horror Picture Show" — 2010-07-05
• "In one era and out the other" phenomenon? — 2009-07-03
• Plot device in some science fiction — 2007-01-19
• Sci-fi subject, or a 1970's dance — 2005-11-23