How do I run X programs on another machine? (NB this is all insecure and for use on your own network)

By default on many installs X disables remote connections with a nolisten parameter to it.

So try and find this by something like sudo grep -n -r nolisten /etc and then comment this out from the appropriate file. Restart X.

Then on a shell on the local machine type xhost + (or alternatively a host name instead of +). Then on the shell on the remote machine type DISPLAY = host:0.0 ; export DISPLAY where host is the hostname of the local machine. Now start your program in the remote shell by typing the commandline startup e.g. openoffice and it will appear on your local desktop.