Nagios configuration and plugins.
Check NFS: a check script to run showmount to an NFS server. Showmount is a great command for checking availability as it is an end to end check including networking, authentication and correct processes.
Check SSL check script to check expiry date of an SSL certificate of a remote HTTPS server.
My Nagios config files. An uncomplicated, useful Nagios setup, including monitoring LAMP servers, checking an ADSL router and a CUPS networked printer.