Growing the Beard: The albums Autobahn and Radioactivity are where Kraftwerk really began to develop their style, Autobahn being somewhat of a transition between their earlier ambient style and their later one.
Narm Charm: Songs like We Are The Robots and Pocket Calculator run on it.
The song "Mitternacht" off of their Autobahn album.
"Kometenmelodie" from the same album. Especially the transition between the two movements, which involves a sudden high-pitched screech.
Nothing beats the scariness of The Man Machine video. Just see those endless columns of zombies walk somewhere mindlessly, without a single clue why they are doing it.
Sampled Up: Most people never recognize it when bands sample from Kraftwerk, but it happens a lot. A lot of Industrial and EBM acts do it, and their drum beats crop up in hip-hop, especially from the 80s and early 90s all the time.
Seinfeld Is Unfunny: By the 1980's Kraftwerk was suffering from this, because by then synthesized music was everywhere.
This one is especially sad, as newer generations are not likely to recognize them for what they did.