Is there a piece of hardware that can connect two monitors to a single video port?  I want to fool an Xbox into thinking that it's connected to a single monitor, when in fact that display area is made up of two monitors on top of each-other.  Something like this:--------------|            ||            ||            ||------------||            ||            ||            |--------------The Xbox would only see then outer rectangle, not realizing that there are two monitors present.  Does such an adapter exist?
Split XBox Screen across multiple monitors
hdmi;video adapters
What you're looking for is called a Video Wall Controller. These are the boxes that you see behind the massive arrays of screens showing a single composited image in the big chain stores. They usually run around a $1000 or more. Without knowing the monitors involved I can't make a recommendation on which one to use. I know of no such products priced at private consumer levels, since usually that part of the market just uses a PC with two video outs to achieve the same thing (except, of course, that the video source has to come from the PC. You might try to rig up something with an HDMI-in capture card being passed out to two HDMI ports off a PC, but you wouldn't probably get true extended screen support - more like you'd have to span the image in a window drawn across both screens. Alas).