Does anyone know of a software package for OS X that allows you to extend your desktop to multiple machines?

Basically, to be able to use a second computer or laptop like a second display. I do NOT mean VNC or synergy or anything like that. Moving the mouse/keyboard seamlessly between computers isn't desktop extension, I want to be able to drag whole windows/apps across like the second machine is just another display hooked to the first computer.

There's one or two packages for Windows floating about that offer this functionality but I've heard of nothing for OS X!! It would be perfect for editing in Final Cut since I've got a million laptops doing nothing, and no standalone displays.

One solution was to install a virtual graphics card driver that outputs to VNC and connecting to that with a VNC client using a laptop. Would've worked if it didn't consistently brick my machine on every attempt

Any help greatly appreciated!