One man who took the vow of 'Never again' more seriously than most was Rabbi Meir Kahane HY"D.
As a Holocaust Memorial Day 'treat,' I have four short videos of Rabbi Kahane fighting the Nazis in Skokie in 1976-77. Especially for those of you whose reaction is disgust, but who have never heard Rabbi Kahane (you know who you are), I urge you to listen to him at least once in your lifetime.