minimal X server/windowmanager

To install X server from a minimal Debian install and make it start on boot:
apt-get install xserver-xorg
apt-get install fluxbox (for example)
apt-get install xinit
put "su -c /usr/bin/X11/startx " in your /etc/rc.local
Make sure the user can start X. Therefor you might have to edit /etc/X11/Xwrapper.config and use: allowed_users=anybody