xosview is the classic system monitoring tool, for Linux, *BSD, HP-UX, IRIX, Solaris and GNU.
As the original project appears to be dead for some time, I created a new repository — starting with the most recent code from CVS, patches from the Debian package, and adding new patches to fix some of the bugs. Development has continued, and this is now the upstream source for several Linux distributions.
The display can be customised and there are some screenshots contributed by users. The old users and devel mailing lists are hosted on Sourceforge; please use these for related discussion.
The most recent release is xosview 1.14 (31st March 2013)
The source code repository is hosted on Github:
$ git clone git://github.com/hills/xosview.git
Licensing terms are varied, and are contained in the source code.