There's a Bruce Sterling story, "Maneki Neko", that's always fascinated me as model for a potential future. In it, a master computer tells people to perform certain actions it knows will fulfill other people's needs. The more you put in, the more you're eligible to get out. It is, in essence, a gift economy organized by the cloud.

It's the sort of idea that seems tantalizingly plausible with smartphones and the cloud, but is hard to actually put into practice. It's definitely the kind of thing that could drive a host of startup ideas, though.

Here's the full story online: http://www.lightspeedmagazine.com/fiction/maneki-neko/