I raised a question here but realized I was going the wrong direction. I need to create a virtual monitor (really just the space in memory) that is large enough to fit a website, that would normally span several screens. Is this possible in any language? I tried Java, but failed miserably so far. I don't expect this to be easy, any pointers would appreciated.
I'd imagine the OS and the video cart would have to told in somehow that there's a third monitor.
Use any Virtualization tool (VirtualBox, VMWare, etc). Create a Windows (XP/newer) virtual machine, and you can attach any number (well, at least up to 64) virtual monitors. All these virtual monitors will open up as separate windows when you start the VM, and you can drag and drop between these windows.
For windows, check out: http://virtualmonitor.github.io/ Right now, it only supports windows 2000 - windows 7, but the developer is looking for help with windows 7 - 8.