For Christmas The Engineer gave me a second monitor for the computer. Not only is he the best most supportive husband ever, he's also very tech savy and can do things like this.
They sit side by side on my desk. And yes, my desk is right in front of a window. This has been one of the nicest things EVER! It is so nice to have the extra monitor space as I'm working on my edits. I can have my WIP open on one side, and a beta's edited copy on the other so I can compare. Or I can have the old version of a scene and my new draft. I can drag things back and forth between monitors if I need to rearrange things. This is one of my favorite tools in my writers toolbox. What's your favorite tool in your toolbox.