John von Neumann

Various links to von Neumann and related work:
A brief outline of the von Neumann architecture for a self replicating system.
John von Neumann.
"John von Neumann: computing's cold warrior", by Nathan Myhrvold.
John von Neumann.
Von Neumann's Universal Constructor
A page discussing artificial self replication is available.
Chapter 5 of Advanced Automation for Space Missions has a discussion of many of von Neumann's ideas, along with a more general discussion of artificial self replication.