The multi-monitor display extension app, spacedesk lets you use other devices and computers on your LAN (Local Area Network) as monitors for your Windows desktop. At least 2 machines are needed to operate spacedesk.
Duet makes your iPad and your Mac more powerful together. Slide Mac apps to your iPad as a second display. No lag, Duet helps you multi-task and work faster with more screen space. It doesn't require internet, just plug and play to get started and you can use the iPad's...
EasyCanvas is an application that allows you to use your iPad as a digitizer.
You can use your PC programs including Photoshop directly using EasyCanvas.