This is a simple guide on setting up X11VNC on a system running Ubuntu 10.04 in a headless configuration. Good Luck, and YMMV.
1. Terminal > sudo apt-get install x11vnc
OR compile x11vnc from source: http://www.karlrunge.com/x11vnc/
2. Terminal > sudo nano /etc/gdm/Init/Default
2.1. Add on the second last line:
/usr/bin/x11vnc -xkb -rfbauth /etc/x11vnc/passwd -o /etc/x11vnc/log -bg -forever
OR if you compiled from source, add the following line:
/usr/local/bin/x11vnc -xkb -rfbauth /etc/x11vnc/passwd -o /etc/x11vnc/log -bg -forever
2.2. Terminal > sudo mkdir /etc/x11vnc
2.3. Terminal > sudo touch /etc/x11vnc/log
2.4. Terminal > sudo x11vnc -storepasswd /etc/x11vnc/passwd
Follow the commands to store your password. Alternatively, if you do not wish to use a password, do not run this line and remove the -rfbauth /etc/x11vnc/passwd section from /etc/gdm/Init/Default
3. Terminal > sudo restart gdm