Open Source

ACM Crossroads: Operating Freely
Description of the 3 major, freely available, Unix-like operating systems: Linux, FreeBSD, NetBSD. Crossroads is the student magazine of the ACM.
http://www.acm.org/crossroads/xrds1-3/free.html

Benchmarking BSD and Linux
Compares FreeBSD 5.1, NetBSD 1.6.1, OpenBSD 3.4; Linux 2.4, 2.5, 2.6; to see how scalable and fast network programs are on standard PC hardware as Web servers; tests several APIs and methods. Text, graphs, benchmark code.
http://bulk.fefe.de/scalability/

COTSE-Mini Unix Distributions
Links to 2 dozen mini Unix distributions: mostly Linux, also FreeBSD, SCO, Solaris MINIX, MINIX.
http://www.cotse.com/miniunix.htm

Linux and BSD, Open Source Giants
Succinct, clear, non-technical introduction to Linux and BSD, focus: how they are relevant to business.
http://shearer.org/en/writing/whatarelinuxbsd.html

Open Source Unix and Related Software Projects
Small page of logos and links to resources, distribution channels for the most popular, freely distributable Unix, and a few other projects. FREENIX links in English, Français, Norsk.
http://www.opensourceunix.com/

PIOS: Pleasant Interactive Operating System
Free Unix clone developed by PIE Software Inc., for x86 PC compatibles, to give a stable multi-user high security platform for use as a network server, programming work-horse, or desktop system; designed so even complex tasks are easy.
http://www.piesoftwareinc.co.uk/