The best song in later year Kraftwerk concerts has without a doubt been "Man-Machine". It is not th ebest song they've ever made, it is'nt even from their best album (which is Trans-Europe Express most of the time, or Autobahn, or one of the two traffic cone adorned albums), but the combination of the “The Man Machine, Machine, Machine, Machine, Machine, Machine, Machine, Machine…” chorus, the dauntingly efficient sound quality, and the larger than large graphics building those exact words, is just unbeatable.
Another good thing with the same name is “Die Mensch Maschine“, a tv program from 1981 that among other things contain a side-view Ralf Hütter talking about being "musik-arbeiter" and bilding their own instruments, and a funny Florian Schneider forming his mouth to "a" and "o" shapes while playing those same vowels from his Texas Instruments calculator while playing “Pocket Calculator”.
Towards the end of the show, Hütter bends his hand into a small cone that he holds up in front of his mouth while singing. A strange fenomenon also discussed (in swedish) in 2002 and, in more detail, in 2004.