Minimise the visual weight of your computer monitors by setting up a background that gives the monitor the illusion of transparency.
Lifehacker reader Louish Pixel could have made his monitor background images anything at all, but he opted to make them a properly scaled photo of the room behind the monitor. In essence, when he's not working in an application that is full screen, you can see what is behind the monitor (although not in real time, obviously). The effect of the room-as-background is a sense that you can see across the room and the monitors aren't quick so monolithic and wall-like.
To set up your background like this just take a photo from the vantage point of your monitor with a neutral focal length like 50mm and then crop it so that the photo shows the room as you would see it from your desk if the monitor wasn't blocking the view.
Transparent Monitors: A Space Enhancing Solution [Lifehacker Workspace Show and Tell Pool]