As you can see, it is possible to monitor a select number of machines using dockapps. Basically you run the dockapp or gnome/kde applet on the machine you want to monitor, but display it on the 'X' display of the server.
By using ssh, you can initiate the applet/dockapp from the server. I use a command line such as the following.
ssh -aCXY remotehost \"asmon\"
It is important to note that, at least for debian, one needs the package xbase-clients installed on the machine running the applet in order to run X applets