It occurs to me that LiveJournal already has a form of currency... we just don't know what to do with it. We'd also want to expand this form of currency to all our users, so that a real economy develops.
It's quite possible to give people points for all sorts of things, such as paying for membership, etc. Theoretically, these points could be exchanged for paid accounts, loaned to others, gambled over friendly games of online poker, etc. They could also be used to buy, sell, and exchange services between LiveJournal users and used by LiveJournal to buy services from its users - a barter system, basically.
It would be fascinating and highly beneficial to LiveJournal... if it could be made to work. Best of all, it would be completely tax free and could actually save people money.
I wonder whether some college somewhere would find the idea of helping create a working Internet-based microeconomy to be a project of interest. I'll have to explore the idea later when I have the time.