The QuadraVista Quad Video KVM Switch from Rose Electronics is the future of KVM switching. This unit supports input of up to four computers, which can be displayed on a single monitor in a variety of ways.
Quad mode divides your monitor into four sections, each showing the output of the connected computers. In addition, PiP mode puts displays one input at full resolution while giving you thumbnails of the other three computers. Full Screen mode allows you to view one computer at full resolution without any other computers being displayed. You have full control over connected computers in any of the modes.
On screen menus make set-up a breeze and keyboard commands as well as front panel buttons can be used to quickly switch between desktops. VGA and
DVI are both supported, so you can connect a wide variety of computer configurations to this KVM. Both
USB and PS/2 computers are also supported.
Here is an example setup using the QuadVista KVM:

Click
here for a datasheet on this unit.