His song. Starting to spot a theme here? Trust me, it isn't intentional, but the more good links I find about Joy Division, the more often I'll post them. The linked article is a nice reflection on their most famous song, especially since it was release after Ian Curtis's death.
This was the song that introduced me to the band back in the early 80s, so it's an interesting read on it's importance and why noone has ever been able to cover this particular song effectively.