The Perfect Server - CentOS 5.7
http://www.howtoforge.com/perfect-server-centos-5.7-x86_64-ispconfig-2

"This tutorial shows how to set up a CentOS 5.7 server (x86_64) that offers all services needed by ISPs and web hosters: Apache web server (SSL-capable), Postfix mail server with SMTP-AUTH and TLS, BIND DNS server, Proftpd FTP server, MySQL server, Dovecot POP3/IMAP, Quota, Firewall, etc."

Linux Fundamentals, Part 1 

DIY: Destroy data on drives via a Linux live distro

http://www.techrepublic.com/blog/doityourself-it-guy/diy-destroy-data-on-drives-via-a-linux-live-distro/835

How to lock down Linux

"Any operating system can be cracked if you don’t adequately protect it. Yes, even Linux. Here are some security basics on how to protect your Linux systems."