Hi, I don't have time to write documentation right now, but the program is fully functionnal. Feel free to grab the tarball and give it a try.
WMgMon is a generic monitor applet for WindowMaker and Afterstep. It can display CPU, I/O, memory, and swap usage, as WMMon does. It can also display the result of other programs, as WMScript does. The result can be displayed as a gauge, a histogram, a percentage, a number, or any combination of those. WMgMon's advantage is that it lets you configure what's displayed in its configuration file so that you can tailor it to your preferences and easily extend it by adding new monitoring functions and new scripts.
Basically, you just have to untar it, go to that directory, type make and copy the resulting file from bin/ to wherever you want it to be (/usr/bin/X11/ is my guess), then copy the sample configuration file from doc/WMgMon to your ~/GNUstep/Defaults/ directory.
Take a look at the config file (WMgMon). If you do not manage to figure out how it works, you'll have to wait for me to write some documentation. Else, enjoy!
Please consider contributing anything useful to this package: sample config files, useful "script lines" or scripts, new or better "update_stat" functions, bugfixes, documentation, new graphics, tool for writing the config file... all of those will be most welcome, as I'll have a little time to maintain a repository of your contributions, but certainly not to write everything myself.
Download it from the ftp site. The latest version is 0.4.0 (13-dec-2000). The main site is at Logilab.