If I want to keep an eye on something, I can drag its window over to the rightmost monitor, and then switch, continuing to work with the other two.
It's the only thing that makes using Microsoft Windows bearable -- being able to switch to another machine on the fly if, say, Windows Explorer decides to ponder for a few minutes over every peripheral attached to my machine just in case I wanted to use one of them. Plus having some Linux boxes just a button-press away.
Each of the machines has a window manager that allows me to switch between different virtual "screens" of information. I like being able to maximize a window and still ignore it.
Some of these virtual windows are running remote control software showing me the screens of still more machines in other locations. (If the machine maintaining that remote control viewing window gets overloaded, I can open another remote control view of the remote machine from one of my other machines, which causes the 'stuck' one to disconnect.)
I want the interface Tom Cruise was using in _Minority Report_. I wave my hands around like that inside my head all the time.
 run, little monitors! You cannot escape!
 I've also taken to putting an extra USB mouse on my primary machine, so I can switch hands without dragging the mouse's tail. I've taught my hands to cross the reflexes so I can move a mouse to either side of the keyboard without having to swap the left and right mouse buttons. I just use them 'backwards' when on the left side. (My cow-orkers have learned not to bother trying to use my machines.)
 I'll bet that's why the default starting folder for explorer is now the inane "My Documents" instead of the list of devices in "My Computer". Don't get me started on the information theory/grammatical problems involved when a machine thinks it knows whose Documents these are. I spend more time on other people's machines than my own, these Documents are NOT mine! Or, as I prefer to say, the machine thinks that IT owns the Documents I might consider mine. Regedit is our (fair-weather) friend.