There's some new 'notes' appearing now, too, as a hedge against these instabilities. They are called "Goldbacks" and consist of a dollar-bill-like piece of specified gold leaf (which is the value) laminated in plastic and a designation, like "$3 note". They are like artwork, here's one example:
https://www.goldback.com/exchange-rateand as they have real gold leaf inside that can't be easily changed, their value against the $ or Yen (or whatever) is always following a more 'solid' valuation per the daily market (unlike cybercoins that change for all sorts of reasons). One good way to watch how the "value" of the Dollar is doing is to watch how much these goldbacks trade for every day. It's an interesting concept, so long as gold remains the world's reserve value material.
Gold coins SEEM like a good way to 'hold value', except they suffer real high commissions when being turned into or out of currency.
I might get some of these flexi-gold 'bars', just to see what they are like?