Does anybody know if there exists a "free to use" grid/distributed computing network? As in, a cluster of volunteers in the grid, such as those that contribute to something like seti@home, but that is free to use by any of the people that contribute to it? If not, would there be any way to say... create a networked grid of computers, with thousands of nodes all accross the internet, and have the users run a server on their computer that would use spare processor cycles, memory, storage space, etc, and have them all clustered togather, in a useful fassion, and also in a way that any one of those contributors could log onto the network in a unix/linux/whatever environment and run programs of processor/memory/storage intensive nature, and have the users of the network's processors scheduled against however much time they put into the project?
I was just wondering if this has ever been done before, or if it's even feasable, or would be clobbered by bandwidth bottlenecks and leeches and such to the point where the end user wouldn't get any gain out of being on the network. Also, if it has been done, could somebody point me in the dirrection as to where I could find a project of this nature?