The iPad is already a pretty powerful tablet you can use to get things done. But you may be able to do even more when you use it as a second display. Here are 2 accessories that let you use your iPad as a second display:
Twelve South HoverBar: an adjustable arm for iPad, iPad Air, and iPad Mini. It clamps to almost anything for hands-free use of your iPad.
Mountie: lets you attach your iPhone or iPad Mini to your MacBook to use it as a second display. It is lightweight and straightforward to use.
Thanks to apps such as Duet Display, you can extend your Mac to your iPad. The above products simply hold your iPad, so you can use it with your Mac more conveniently.