The Nagios Grapher contrib is no longer supported.
The Nagios contrib now includes the PNP graphical perfomance data analyser. PNP integrates much better into Nagios 3 than Nagios Grapher. In contrast to Nagios Grpaher, PNP is under ongoing development and much better documented.
Last version version of the page: http://wiki.contribs.org/index.php?title=Nagios_Grapher&oldid=11537