Administration on Systems w/ Lots of Users?

kidlinux asks: "Since I started using Linux I've relied mostly on documentation to learn how to use any given aspect of the system. Up until now, I've been used to setting up systems for myself and a few of my friends. I have recently been hired to setup a system which will have 100+ users. Some will have shell access, some email only, some web access, etc.. When setting up a system for vast amounts of users, are things done differently? What kind of things do I need to consider when configuring the system? Is there any documentation available for setting up large scale systems?"