A professor and science fiction author who wrote a lot of influential SF on themes of interest to geeks.
Many people know him through two famous short stories: "True Names", which influenced cypherpunks and virtual reality fans, and "The Ungoverned" (based on the ideas of The Machinery of Freedom), which influenced libertarians.
Also the author of The Peace War and Marooned in Realtime (recently collected as Across Realtime). See The Vernor Vinge Project for more details.