Cloud Computing has been the Hot Stuff, but now what? Application Ideas? Post em!

Ok so some readers who have a lot better handle on this may find a mistake or two, but here is a basic description I wrote up for my father, who was asking about what it really was. He needs to know, he works in publishing. The question is, what are some great applications for the cloud that cannot be done with our normal infrastructure?

"Cloud Computing I understand it reasonably well. Remember that before computers became PCs on the desktop, they were mainframes? Then, every user had a terminal, but all the processing was done on a larger computer - the terminal was just the control station where you interacted with the mainframe. Cloud computing is very much going back in this direction. Instead of processing being done on your home computer or your smart phone or whatever, it is done by a larger "computer" somewhere else. The difference now is that this larger computer is not one mainframe, but a giant (and I mean giant) network of computers working together. This is the cloud. Together they have the power to process lots of requests. You can think of what Google does as cloud computing sort of since they have vast warehouses of servers stacked up, each of which is really a pretty humble machine, but working together they form a supercomputer, and with it, they give people access to services. Google docs is a very cloud computing type application, because they take what is normally a desktop application (word processing lets say) and make it into a network application - you just access the internet and use the program running in the cloud. This is why Microsoft is afraid of Google, because if Google does enough of this, the valuable windows operating system becomes obsolete. The crazy thing is that in cloud computing, your computer can become part of the cloud too though. Conceivably, the cloud could be the whole internet if everyone participated."