Duet Display : Use your iDevice as an extra display for your Mac

Duet is the first app that allows you to use your iDevice as an extra display for your Mac using the Lightning or 30-pin cable. Duet is built by ex-Apple engineers, delivering a retina display at 60 frames per second with no lag. Seriously.

You can also choose between 60 and 30 fps. Duet Display is simple, but it's fast, easy to use, and works great.

Download Duet Display for iOS ($14.99) 

Download Duet Display for Mac (Free)