Neuromancer

Neuromancer - William Gibson

This was the first cyberpunk novel I ever read, and I fell in love with the genre instantly.  The writing is amazing, starting with the first paragraph and going right to the end.  He took story telling to an entirely new level and created a genre at the same time (sure, there were a few before him, but he wrote the definitive cyberpunk novel).  He has an amazing style.