Aviation

The original, 1916 version of the Aviation included crème de violette, a violet-flavored liqueur that tinted the drink a pale sky blue (hence its name, some say). Not much later, the liqueur became nearly impossible to find in the US, and this version of the drink—without any crème de violette—became the standard. (Ironically, at least three new brands of crème de violette have launched within the last decade.) Slideshow: More Great Gin Cocktails