The NSA have published a 170-page security configuration guide for RHEL5. It’s a kind of best practices document for security, with step-by-step explanations for locking down pretty much every feature of the OS.
I’d say this is essential reading for anyone deploying RHEL or similar (Fedora, CentOS etc.) distributions, and likely also quite useful in the general case.
Seems like ideal reading during travel to FOSS.IN :-)