Interesting points brought up in this thread.
As far as alternative currencies in the USA, in may of this year the state of Utah passed a bill in their legislature allowing gold and silver to be used as currency. Utah also abolished state capital gains taxes on sales of gold and silver, though the Federal tax still applies. This is an interesting development, the question is whether Utah will be marginalized or become the trendsetter for the rest of the nation.
In the current issue of
Digital Gold Currency Magazine, on page 40, there is the South Carolina senate bill to allow gold/silver as legal tender. I read before that it's in the works in other states also...