More things to discuss:

* In /etc/nagios2/conf.d/ the files:
   - generic-host_nagios2.cfg
   - generic-service_nagios2.cfg
  and how hosts and services inherent from these.

* The idea of flapping.
* the idea of failure prediction.
* In the graphical interface lots more info to be had:
   - Event log
   - Performance Info
   - Scheduling Queue

  But, more importantly, the Reporting section has good stuff, like
   - Trends
   - Availability
   etc... 
  And, be sure to point out that you can filter much of this. Such
  as filtering on Alert History, etc...

* The event log
* Configuration - allows you to see how things are related.

* All this good for executive level reporting.

* In addition the nagios open pipe that is availabe to push state. On 
  Debian/Ubuntu this is in /var/lib/nagios2/rw 

  Discuss the script /var/www/share/files/submit_check_result, which 
  is Perl. Go over this in the scripting discussion.