Use one big computer, with a multi CPU motherboard, a few video card's and a very lot of USB ports.
Then if you would be able to connect, for example 4, monitors, keyboards and mice to it, it would be very nice if you could work on the same computer with(in this case) 4 people at the time. You could give every one of them a private desktop, enable multiple cursor support. Or give them all a private account, and let them just do their own tasks on one single computer
If you would be able to let every one use the same user account at the same time, only with everyone a personal desktop, then it would be useful during, for example, a photoshop lesson, so that the teacher can help it's pupils by navigating to their desktop and fiddle around with his cursor(and keyboard, in some clever way), and that those pupils can look at the desktop of their teacher, so that would save a very lot of explanation.
Or else, in a public library, where there are a very lot of computers preforming small tasks, you could give them all a separate account, and preform all that lightweight tasks on one computer.
Or on schools, it would be easier with swapping files between students working on a project, and/or they can have a look at each others desktop if they want to show something to another.
And at last, in just a home network, it would be a lot of fumbling with cables, and the only things that are improving is files swapping, and the overall usability, because you can do everything from everywhere, because all app's are on the same computer. Oh, and parental control, but i don't like that. ;)
There might be a lot more possibilities, but these are the ones that came up in my mind.
I guess it's gonna be a nightmare to program this, but well, if it's your hobby... :)
I guess there is a lot of improvement possible to my way of presenting this, but i don't find it bad for the first time of posting an idea.
Greetz,
Yur