There's a certain beauty to the idea of split-screen co-op games - you get to be in the same room as your partner, staring in the same direction, and working together to accomplish a goal. The problem with split-screen though is that it splits the screen in half. If only there was a way to have the good parts of split-screen, but without having to compromise your precious screen-space!
Because this is the internet, anything you CAN imagine already exists somewhere. And, of course, someone has created their own split-screen (for Borderlands) by stacking two TVs atop one another.
Hats off to you, internet-person with way too much money and time on their hands.