A friend wrote the basic information that I expanded into this guide: Debian Linux cryptocoin mining rig setup
The guide takes you through the Debian install, the driver and SDK install, the cgminer compile, and so on. This can be used on any coin that cgminer supports--that means Litecoin, Bitcoin, every alt, etc. This guide is tailored to AMD GPU users, but NVIDIA users can just use different drivers and cudaMiner (I can't help you with that part). On that note, if someone who uses Linux and NVIDIA can post that information, it would be appreciated.
The donation info on the guide is my friend's address, since without him the extremely minimal and simple guide wouldn't have been possible.
The above system setup is the minimum needed to have your rigs running. That means you can run that system on as low as 512MB RAM. We both use 1GB RAM on our rigs since that's the cheapest you can get these days (2x1GB sets and put 1GB in each rig!).
You can install Apache and PHP and have the monitoring script running (haven't added that info yet but you can figure it out with Google) with absolutely no extra overhead.
You can log in with your favourite SSH program and monitor cgminer (by using Screen).
Edit: I also added the guide to the Litecoin wiki
but it might be out of date compared to the original.