I have a machine that I compile code on and it is very slow, taking 3 hours and more to build. Using top, vmstat and iostat was fine for a quick examination but I wanted something simpler to set up and with good output. I have used Nagios before and found it to be great for serious monitoring but it requires some level of effort in setting up that I wasn't ready for here so I tried a more lightweight solution, Munin.
Munin installs as either a server or a node in about 30 seconds (from rpm) or a few minutes from source. Configuration is simple and straightforward, documentation is adequate and results are just what I needed. Plugins are written in Perl and graphs are drawn by rrdtool (like nagios and cactus).
My linux machine was set up as both server and node in about 3 mins but the Solaris box was a little more tricky. After fixing a server config file foobar and node config file foobar, all was well.
Worth a look..