Duet Display is our favourite "second screen" app for iPad that extends your desktop computer's screen to your iPad. Today, Duet Display gets an update that adds in Touch Bar support, which means you can emulate the new MacBook Pro's Touch Bar on any iPad.
When you connect an iPad running Duet Display to a Mac running Sierra, you'll see an option to enable the Touch Bar. Do so, and your iPad emulates that little bar so you can use it as you see fit. It's a minor improvement, but it might prove useful with some apps.
Duet Display ($14.99) [iTunes App Store]