Gosh, I swear in front of the flying spaghetti monster, that just yesterday I was at my neighbors' house, with two of their gamepads (demanding repair due to joystick drift syndrome) in my hands, without even knowing what I was doing, I placed the two controllers face to face exactly as you did there, the 4 joysticks touching each other. Seeing the multiplication of joints, I thought it would be cool to give it a proper interactive application. It turns out that I stumble upon this page the next night during one of my endless web browsing. Many people may have thought it before and will do it after, but for me, the discovery of your work, is another manifestation of this cosmic dance à laquelle nous somme tous assujettis (sorry for the grammar, English is not my mother tongue)

I tried to tape the joysticks together, but couldn't even manage get pass 5ft speed, can't wait to build a proper interface with the 4 joysticks alone.

You surely know about Alt-Ctrl @ home JAM (it's hosted by MechBird, which work is awesome too) 
Have you planned to submit mutual analogus ? 

Anyway, thanks a lot for all your amazing work, the kind that keeps alive