No , I am not looking for SNMP tools.

Neither is Sinistral.

While I cannot speak to the other tools I know that Nagios allows you to write plugins to do much. If you can write in Perl (or other languages) and the plugin you write returns to the calling environment certain values you can make Nagios do whatever you need.

I've even seen Nagios used to monitor the temperature of a kegerator.

Check out the Nagios exchange. What you need may already be written by somebody.