I know the OP asked for "cool" things to do, but I'll add my vote to
those who suggested highlighting configuration management. I'm not
sure how much puppet or cfengine you teach in a half-day, but I'm
fairly confident you could cover:
1. considering configuration files to be code -- it needs to be in
a repository
2. setting up a Subversion or git repository and some possible ways
of laying out a configuration repository (per host, per service,
etc)
3. committing changes, recovering older configs when newer ones
introduce regressions
Personally, I like Subversion for configuration repositories because
(imo) sysadmins usually like having an authoritative repo rather than
a widely branched one -- but git is on the rise and is certainly worth
considering.
Other, slightly related, suggestions include setting up a
documentation wiki and/or a ticketing system. Trac can do both, but
there are plenty of worthwhile alternatives.
--
Paul Heinlein <> heinlein at madboa.com <> http://www.madboa.com/