Ever since I have an iPad I wanted to use it as a secondary screen. I travel a lot, so a compact external monitor would be really cool to have. It really makes sense: it has a really beautiful high-resolution screen, it’s small, light, easy to carry.
But using it as a secondary display just doesn’t work.
Of course you can use Air Display, but you’ll soon find out that it’s either very slow or displays a terribly compressed image. If you decide to jailbreak, check out this blogpost, which explains how to communicate with your iPad using the usb cable.
But if you just want to display a terminal window, you can get away a lot more easily: