Take a closer look at OpenBSD with Tim McIntire. This is a quick and nice introduction to OpenBSD.
FTA, “OpenBSD is quite possibly the most secure operating system on the planet. Every step of the development process focuses on building a secure, open, and free platform. UNIX and Linux administrators take note: Without realizing it, you probably use tools ported from OpenBSD every day. Maybe it’s time to give the whole operating system a closer look.
When security is of the utmost importance, it’s only logical to look to the same operating system that spawned today’s standard in secure remote access, OpenSSH (Open Secure Shell). OpenSSH is just one part of OpenBSD, a distribution that has focused on security from the ground up, accomplishing a goal of creating a UNIXÂ®-like operating system that is secure by default.”
Read more at IBM developerworks