I really like this article about FreeBSD. One really nice feature that is not cover though is to set the immutable flags on some binaries with the command chflags. It's possible to boot your very secure system into securemode level 1 or higher. In this mode, it's impossible to delete those files.
rm -rf /* has very limited damage.
chmod -R 0000 /* won't touch chmod and all kind of ooops become much less destructive.
It's probably not useful in all scenarios, but definitely some systems deserve to never be touch live. Automation, scada, super important core backbone systems.
FreeBSD is the power to serve. It deserves more credits.
In case anyone is interested, I can help you with SYN flood, amplification attack, volumetric attack, rate-limiting botnets and also against spoofed attacks.