i'm not ignoring all of the suggestions so far (i'm taking note of all of them) but as rp herrold suggests, a lot of this is getting pretty far afield, so let me drag this back on-topic.
i'm looking for cool things that can be added into a very generic 5-day course in basic RHEL (centos) administration that wouldn't normally be covered. i've provided the outline on which the 3rd party courseware is based -- it was written to mimic red hat's RH 131 course:
https://www.redhat.com/courses/rh131_red_hat_linux_system_administration/
so you can see what's already there, and i'm after cool tips, tricks and utilities that people who are long-time RHEL/centos admins have learned that they think are terrifically useful that i can sneak in as bonus content.
the caveat is that i don't want to add topics that would take longer than, say, a half day since i can always take a topic like that, extend it to a full-day course, and market it *separately*.
case in point: virtualization. the course already covers virtualization *very* briefly and i don't want to make that section any longer since i can easily see having a full-day course on that topic.
*possibly* the same thing with puppet or cfengine (both excellent suggestions). i'm thinking of at least demoing one or both and, depending on the interest, perhaps suggesting a full day course in enterprise-wide administration.
anyway, i appreciate all of the ideas so far, and i'm definitely going to use some of them. thanks muchly.
rday
p.s. one stupendously trivial idea i had was to give each student a cheap USB drive and use that as the vehicle for playing with filesystem utilities. with an $8 2G drive, i can demonstrate concepts like hotplugging, udev, LVM and so on, knowing i'll never risk the contents of the hard drive.