The FreeNAS website touts itself as "the most potent and rock-solid open source NAS software," and it counts the United Nations, The Salvation Army, The University of Florida, the Department of Homeland Security, Dr. Phil, Reuters, Michigan State University and Disney among its users. You can use it to turn standard hardware into a BSD-based NAS device, or you can purchase supported, pre-configured TrueNAS appliances based on the same software. Operating System: FreeBSD http://freenas.org/