Don't-Miss Display Stories
The $15 iOS app, Duet Display, allows you to use your iPad as an external display. Thanks to its wire requirement, that display is actually responsive.
No complaints about eliminating superfluous features to shrink the price tag; but you can't compromise build quality, too.
If you're looking for a way to raise your iMac or Apple Display to a more-ergnomic height, the HiRise for iMac does just that while giving you some extra gadget-hiding space.