[yajoe]

Yes, many public stocks on major exchanges are just other forms of currency. It just depends on whether the underlying asset is highly liquid (which implies easy to trade, confidence it will exist in short and long terms, etc). I would humbly submit not to get hung up on the word 'virtual' since the practice of using stocks as a liquidity source (and at times to actually print money) have been done a few times in the past.

My favorite example is from the 1890s: Amalgamated Copper

Summary: http://www.jstor.org/stable/1884999

Book describing the process of getting banks to print money by ficticously reporting assets: http://www.gutenberg.org/ebooks/26330

Had the author written the book today, he would compare the practice to quantitative easing or injecting liquidity: http://en.wikipedia.org/wiki/Quantitative_easing

The big difference? Amalgamated Copper was a private entity whose owners used fraud and banks to print them millions of dollars.