In this article I will describe how you can monitor your Debian Squeeze server with munin and monit. munin produces nifty little graphics about nearly every aspect of your server (load average, memory usage, CPU usage, MySQL throughput, eth0 traffic, etc.) without much configuration, whereas monit checks the availability of services like Apache, MySQL, Postfix
via Server Monitoring With munin And monit On Debian Squeeze | HowtoForge – Linux Howtos and Tutorials.