Luna Display, $65
Got a Mac? Got an iPad? Need a second display? Then try Luna. It turns your iPad into a second screen for your MacBook with little or no fuss.
Simply plug a small dongle into your Macbook – Mini DisplayPort or USB-C versions are both available – and launch a free app to turn your iPad into a wireless display for your main machine.
If you don’t have a wifi connection, you can use USB. Your iPad extras – the Apple Pencil, wireless keyboards etc – will still work, and your Mac gets the added benefit of touch interaction.