Operating Systems
Misc:
The Sysadmin’s Rosetta Stone, a functionality equivalency chart for various versions of UNIX.
Cool Commands has tips and tricks for many UNIX-based operating systems.
Solaris:
Solaris
Linux:
Sun’s Java Desktop System, currently based on SuSE Linux
JDS Help, with software and informational resources for the Java Desktop System
Red Hat Linux
Debian GNU/Linux
SuSE Linux
Linux-Mandrake
Slackware
Graphical User Interfaces / Window Managers:
Window Managers for X guide by Matt Chapman.
Windowmaker is my favorite window manager.
You can find decorative themes for most every window manager in existence at themes.org.
More X11/window manager information can be found at WWW.X11.ORG.