Recently, while writing the document pictured below, I needed to simultaneously view the introduction (which contained several academic citations) with the works cited list, to recall who was arguing what. I'd forgotten about this functionality in Word, but you can split the screen to view two portions of the document simultaneously -- formerly impossible with digital documents and a major affordance of print over on-screen reading.
But I'd been using Excel a lot recently, and I remembered that split screen was available in Word too. So here's an image of splitscreen textual coordination in action.
Coordinating on-screen texts with splitscreen funtionality
By the way, to do this, you grab a little tiny bar over on the scroll bar and drag it to where you want to create the split. You can then scroll each part of the document independently. Nifty!
How to split zee screen -- grab and drag.
Finally, I found myself wanting to do the exact same thing in Adobe Acrobat while reading a .pdf. No such luck. The functionality hasn't migrated beyond MS programs to my knowledge.