DragonFly BSD: Fork of FreeBSD 4.11, focus: scalability, robustness, and debuggability in several broad system traits, especially threading and symetric multiprocessing, SMP

FreeBSD Handbook: Describes the installation, administration and day-to-day use of the OS. Created by the FreeBSD Documentation Project

FreeBSD Project: Official home: the definitive resource for FreeBSD information. Descriptions, downloads, documents, community, developer resources, support

OpenBSD Security: Official OpenBSD security advisories

OpenBSD Support and Consulting: List of individuals and organisations that provide commercial support and consulting for OpenBSD, sorted by country and province

OpenSSH: Free version of the SSH/SecSH protocol suite of network connectivity tools developed by the OpenBSD Project

The FreeBSD Diary: The FreeBSD Diary is a collection of step-by-step how-to entries aimed at UNIX novices

The NetBSD Project: NetBSD is a free multi-platform operating system, with a focus on portability

The OpenBSD Project: Multiplatform Ultra-Secure Operating System. Focus: portability, standardization, correctness, security, and cryptography