VNC also comes in other flavours, with versions for many different operating systems. If you think hard enough you can come up with lots of different possible uses, but one that has proved useful for teaching is the remote control of single user machines.
If you run a VNC server on a MS Windows PC and display the screen on your UNIX workstation (or even another Windows machine) you can control the machine remotely using the vncviewer, if you move the mouse inside your VNC window the mouse cursor on the actual machine will move with it. If you start a VNC server on every machine in a teaching lab then you can flick between them monitoring student progress, useful for remote diagnostic purposes.
Figure: VNC displaying a Windows 98 desktop on a X Windows display.
Figure illustrates this setup, showing a MS Windows
98 desktop (1024768 pixels) being displayed ontop of a
Truecolor X Windows desktop (12801024 pixels) running the WindowMaker window manager on a Linux PC.
The Graphics Cookbook