Valid HTML 4.01!

X tips and tricks
X is the graphics server used by Linux, Xfree86 used to be the most widespread, now x.org seems more common. These are a few hints I have used.
xset used for setting x parameters, I have used it for setting font paths, eg.
xset +fp tcp/xx.xx.xx.xx:7100
7100 is the port of the font server on the remote host.
Xnest runs a new X session inside an existing one. I use it to get a desktop from a remote machine, usually a Solaris box at work, eg.
Xnest :1 -query xx.xx.xx.xx &
The :1 says which X session to connect to, -query invites a login on the remote host.
If your current machine doesn't have the correct fonts for the remote machine to use, typically you will get a login box, bat after correct passwords are entered, the remote host will invite another login. This can be solved by using xset to set the font path as above. Not all machines run a font server.
Screen Capture, xwd (X Window Dump).
xwd write to std out, but the -out switch allows a path to a file to be specified. To take a screen shot of an individual window, use:-
$ xwd -out /tmp/window.png
If you want to capture the whole root window, use:-
$ xwd -root -out /tmp/screen.png
xwd seems to support several file types.