Over the years the concept evolved from spending spree vouchers to gift cards to, well the ultimate voucher, cash: the universally tradable commodity.

FORBES: Do Yourself A Favor And "Voucherize" The Christmas Thing

Some professional money managers are starting to treat commodities as a tradable asset class, which bothers some traditional investors as each commodity has different supply and demand fundamentals.

FORBES: INTERVIEW: Inflation Should Not Be A Problem For U.S., Canada, Gold Prices To Rise -- Dundee's Murenbeeld