Laptop as KVM ?

Here's a device that I would like to see... USB connector on one side...
KVM connectors on the other side. I would then plug the USB side into my
laptop and the KVM side into a computer. Then I would startup a program
that would display the video output of the computer in a window on my
laptop and allow me to interact with the system as if I was connected with
a normal keyboard/mouse/monitor (just like VNC). My motivation here is to
use my laptop to access the BIOS and other firmware of an x86 box without
having to cart around a monitor and keyboard.
The KVM-to-ethernet devices are just a tad bit expensive, unfortunately.
Or maybe this device already exists and I just haven't found it yet...
~M