NagiosGrapher collects the output of NagiosPlugins and generates graphs.http://www.netways.de/de/produkte/nagios/erweiterungen/nagiosgrapher/
The "NETWAYS Nagios Grapher" is a Graphing system which uses templates to
assign services to various data sources (RRDs). Thus it is possible to
create a quantity of graphs using only a small configuration, keeping it
easy to manage. These templates are automatically applied to incoming
data, thus creating a new service in Nagios will automatically create the
graph once valid data is seen for that service. Corrolations between
different graphs is also possible.