Reverse Cloud Computing

When I first heard about cloud computing, I assumed it meant the exact opposite of what it actually implies.

No. I didn't make that myself. Its from Wikipedia.

Basically, cloud computing is just the use of computing resources over a network. However, it has come to describe the services provided by large companies to individual devices over the internet.

What would be the reverse? Individual devices providing computing resources to companies. Think for a second about all the computers doing absolutely nothing at this moment. What if all that computing power being harnessed, somehow?

One way to do it might be to pay people for the use of their unoccupied computers. Then, whenever someone is not using their computer, it can be connected to a server over the internet and used by someone else. This seems like a win win situation to me.

Imagine that an animation company is attempting to render some 3D footage by a deadline. If they don't have enough computing power to finish it on time, they could just pay some provider for the extra resources. Then, the provider connects with a bunch of the computers it has registered in order to perform the additional rendering. The people get paid for doing absolutely nothing, the provider takes a piece, and the company finishes on time. A win win win!

I don't know whether this has already been implemented or if there are reasons why it would not be so useful. Nonetheless, it is certainly a neat idea.