Friedrich Nietzsche is an unusual influence in philosophy in that his works were not considered significant until well after his death. He drew from many different sources to create his ideas of philosophy, and was one of the first philosophers to focus extensively on the self instead of on the collective. This allowed a focus on personal growth and the elimination of "messy" religious influence, which was still common in philosophy while Nietzsche was writing ("messy" does not denote negativity, but refers to the complications that religious influence has on pure philosophical ideas). Nietzsche's influence on Nazi Germany was largely the result of misinterpretation and selective reading, but cannot be ignored; Richard Nixon read Nietzsche extensively, and modern-day anarchist movements draw selectively from Nietzsche's works.
Nietzsche served as a staunch proponent of individualism, which formerly had been ignored in favor of altruistic collectivism; he showed that the individual is just as important as society, if not more so, and claimed that life was meaningless unless lived with intent. This affected many future philosophers in dealing with questions of meaning and purpose both in human life and in the existence of the universe itself. To this day, Nietzsche's works are drawn on in almost every field of art, literature, and philosophy, whether to deconstruct them or as foundations for building new ideas.
When Nietzsche writes that he is committed to following truth "wherever it leads him," I think that it is a telling moment both in his life and in the reason why he is so important from a philosophical point of view. Nietzsche's importance was that he was one of but a handful of thinkers that truly cared about his place in philosophical thought. He allied himself with luminaries such as Wagner and Schopenhauer. Yet, when he was convinced that part of his way of thought was not represented with such alliances, he severed connection with them because of in-authenticity. Nietzsche spends much of his life isolated because of this, demonstrating that the modern thinker and philosopher has to remain true to their love of wisdom, and worship of ideas. From the intellectual point of view, his questioning of human motivation and the essence of humanity is essential in understanding both the Modernist and Postmodern movements. Both modes of thought in the 20th Century owe much in way of debt to Nietzsche because he ends up making it easier for them to develop as viable modes of thought. His desire to understand what it is that humanity's essence is outside of the constructs of social acceptance are significant in that they end up setting the stage for thinkers like Freud and Jung as well as the Deconstructionists like Derrida and Foucault, making Nietzsche highly significant to the discourse.