What is Duet?
Duet is for people who lack screen real estate. It allows you to use your iPad / iPhone as extra displays for your mac. All this without lag.
It’s made by ex-Apple engineers. Take a look here www.duetdisplay.com/.
Why & How I use Duet?
I mainly use it while on the run and while not being connected to the Thunderbolt Display. Usually I send reference materials, notes and such to the Duet screen. Duet definitely increase my productivity and focus by allowing me to not switch windows all the time.