For years I've been using MRTG, RRDtool, SNMP and dozens of my own scripts and services to monitor all my servers. While it was all working fine it needed way too much time to setup, configure and maintain each host.
I've switched to Munin which is great tool, but I don't like default graphs it provides, not to mention that it doesn't have plugins for some things I've been monitoring. Thankfully Munin and most of its plugins are written in Perl just like my old monitoring scripts so I'm now porting my old system to Munin as well as writing new plugins.
Sorry :-( This sections is not complete yet.
If you are using my Munin plugins please consider donating me.