Howtoforge posted a guide about setting up Server Monitoring with munin and monit on Debian 7

In this article I will describe how you can monitor your Debian Wheezy server with munin and monit. munin produces nifty little graphics about nearly every aspect of your server without much configuration, whereas monit checks the availability of services like Apache, MySQL, Postfix and takes the appropriate action such as a restart if it finds a service is not behaving as expected. The combination of the two gives you full monitoring: graphics that lets you recognize current or upcoming problems, and a watchdog that ensures the availability of the monitored services.

  Server Monitoring With munin And monit On Debian Wheezy