Have you noticed that, when you open an X-Server on your box, the system will open the port 7000 (thats the standard)? So it seems possible to connect to this port and trasmit the graphic data over a network(i.e. the internet). For this to be possible you have to do the following configuration steps:
“xhost +[ip]” whereas [ip] is the IP of the client
“export DISPLAY=”[ip]:0“ whereas [ip] is the IP of the client
After doing this all programs that use X which are executed on the server will be visible and controllable on the client. The CPU time used by the program, however, will be the server one's.
Thats pretty much it. I hope that wasn't too cryptic. Have fun.