iDisplay Desktop for Windows lets you add your iPad, iPhone, or iPod Touch as an extension of your desktop display for more viewing space. With this app, you can declutter your desktop viewing area while still being able to see all windows you need.
Installing iDisplay is a little bit complicated and takes some time. Depending on what you already have installed on your computer, you'll have to install one or two additional programs, so that the app runs properly. The app will also have to scan your display for compatibility, which can take between five and ten minutes to complete. Once that's done, however, the app runs automatically from the task bar in the bottom right-hand corner of your screen. There is no Help file, which would be nice to have in the beginning, but once you get the hang of the app, it works seamlessly and intuitively. From the Settings menu, you can drag the images of connected screens to mirror your desired configuration, and then just use all additional screens as an extension of your desktop. The mouse will move from one screen to the other, and to move a window or icon, just drag and drop it in whatever location you'd like.
You do have to install the companion app on whatever device you want to use as your additional screen, and this costs $4.99, but you only have to purchase it once for all of the devices you want to add as long as they're on the same iTunes account. Overall, this app has nice features and an intuitive interface, so if you often find yourself wishing you had an extra screen it's a good program to try.