I remember being blown away by the platform side doors for the shinkansen bullet train in Japan: the incredible precision with which the train doors align with the platform doors.
Not sure... one of the Tokyo stations I think. It was still an open air platform, but had doors on the edge of the platform around man-height that aligned with the train doors.
(Also, London has had platform edge doors for a while already - only on half of one line, but still)