The folks behind Duet Display have released a Windows client, allowing you to extend your machine to any iOS device.
Plugging in a second monitor to extend your computer from one display to two is just about as far from a new concept as you can get, but taking an existing piece of technology and using it as a second monitor temporarily is something of a challenge. Duet Display was the first app to make an iOS device into a 60fps second monitor with touch input for OSX, and it remains one of the best experiences for temporarily extending your desktop setup when you're on the go.
Until today, this experience was limited to Mac users with iOS devices. With Windows support now available, Duet Display can now be used to extend the desktop of just about every computer on the planet. We've been using Duet for Windows for a couple of days now, and while it's not yet perfect the experience is thoroughly enjoyable.
Much like the OSX client, Duet Display for Windows is designed to be plug and play. You install the Windows client, open the app on the iPad, and as soon as you connect the Lightning cable to the PC the OS treats the device like a second monitor. A brief flicker occurs and you can now drag applications from one desktop to another, exactly as though you had a monitor connected via HDMI. The touch panel on the iPad works like mouse input, which means you don't get swipe gestures like you would on a native touch device but you can still poke and double tap to open and adjust things.
It's early days for Windows support, and as a result there's a few setups that don't work quite right. In our testing, SLI configurations aren't fully supported yet. Installing Duet Display on these setups will cause immediate problems on reboot, but uninstalling the app will quickly eliminate those problems. In talking to the developer, these problems will likely be resolved quickly. Every other environment we have available handled the app just fine, with exception to an occasional stutter in the Windows 8 full screen start menu.
This is by far the most elegant portable multi-monitor display out there today, especially if you're already using an iPad and a laptop on a regular basis. Duet Display is available today in the App Store for $15.99, with the Windows and Mac clients available on the Duet Website.