Howtoforge published a guide about monitoring multiple systems with munin under Debian GNU/Linux 4.0

In this article I will describe how you can monitor multiple systems with munin. 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. I will install the munin client on all systems that are to be monitored (including the munin server itself); the munin clients will then report to the munin server.

Monitoring Multiple Systems With munin (Debian Etch)