Ridiculously simple NTLM Authentication for Apache (Ubuntu)
We all know Ubuntu makes things amazingly simple. This is the best I've found so far. NTLM authentication in Apache used to take a while to setup, it used to be tricky, fiddly - generally a bit hit and miss.
Installing mytop on cpanel

MyTop is one of the best MySQL monitoring tools available, written by a MySQL guru, Jeremy Zawodny.
Its vital for monitoring your MySQL health, especially in a shared hosting environment.
mod_geoip Revisted including stopping spam in phpBB 2
I've recently moved a client's forum onto a new cPanel server, previously it was on a home-brew Ubuntu server.
So I had to install mod_geoip onto cPanel in CentOS. It wasn't as bad as I was expecting.
First off, we need to download the GeoIP libraries.
Ubuntu Upgrades
Here is a really simple way of upgrading your Ubuntu system. After the initial setup, upgrading to Karmic or Intrepid is a one liner.
[Snippet] Installation of MS SQL Libraries on Ubuntu
Can't find php-mssql? Nah, its gone. Use php-sybase which contains both libraries now. Remember, make sure FreeTDS is installed aswell.
Installing mod_evasive on cPanel and/or Apache
This guide details how to install mod_evasive on cPanel to help protect against DDOS attacks, brute force attacks and other irritants.
It uses an internal hash table of IPs and URLs and can temporarily block web requests to anyone requesting a large number of page views, or making many concurrent requests. Properly configured it can help evade DDOS attacks and keep your customers happy.
You can integrate it with iptables and hardware firewalls too if you like.
Enabling mod_deflate/gzip globally on cPanel
There's far too many reasons to mention why you should enable mod_deflate to gzip your content served by Apache. Simply put, it makes it go fast.
You can enable mod_deflate in cPanel really easily with /scripts/easyapache. Easy.
Installing memcached on CentOS (cPanel)
Welcome to hell. No really, compared to installing memcached on Ubuntu, CentOSs really sucks. CentOS really sucks for package management. Really sucks. Anyway, on to the point.
Here's how I installed memcached on CentOS, which I mainly use for cPanel.
[Snippet] CentOS Server Firewall Configuration
CentOS 5 Server has a nice text interface to configuring your firewall.
system-config-securitylevel-tuiSimple install of memcached on Ubuntu
Memcached is a free, high performance distributed memory object caching system. In English, it can make your single server PHP applications faster or for a little more technical users you can write cache and share cache objects over a web server farm or cluster. Great, eh.
No seriously, it can really make your PHP faster.