Muliple Monitors on a Single Computer
This is a hit or miss proposition depending on your video cards and monitors, but it worth the trouble if you can get it working.
Laptops are especially likely to use this configuration when they attach an external display. It is useful to shut off the LCD output to get correct fullscreen operation of programs which use the SDL software library. The laptop LCD can be shut off with the command:
xrandr --output LVDS --off
xset dpms force off
may work as well if the LCD is another X Windows display rather than output on the same X Windows display.
It may be able to turn off the LVDS output (LCD) via the xorg.conf configuration file as well.
DualMonitorDualServerOneInput - Two monitors, two video cards, running two separate X servers but sharing a single keyboard and mouse