Some Munin plugins I've written. See the project http://munin.projects.linpro.no/ for details of what that might mean.
Structure is as used in the Munin source tree (browsable here: http://munin-monitoring.org/browser/trunk/plugins). Those in node.d/ are platform-independent, those in node.d.linux/ most likely require Linux-specific functionality.
Most of these are still works in progress, so unless explicitly noted otherwise, breaking changes may occur at any time. That may mean losing graph history, or having to re-configure the node to avoid gaps.
This is just a brief overview of available plugins. The plugins should (eventually) contain more detailed documentation in POD format.
node.d/nagiostats_-
Statistics relating to Nagios performance. Mostly works, should be fairly stable.
node.d.linux/cpuidle(requires multigraph)-
Monitor usage of CPU idle states. Still very raw, both in terms of the code as well as the usefulness of the graphs.
Wherever possible, they should work cleanly with munin-node-configure. See individual plugins for specific caveats.