With gold at sky-high prices, speculators are jumping in and raising the prices, potentially creating mini-bubbles. Even without their presence, diversifying across products protects you from inflation and mini or major bubbles. Here’s an article about investing in other metals such as rhodium and uranium; agricultural products such as wheat and soybeans, and water, already used as currency in unstable environments such as Haiti and Afghanistan and potentially valuable in high-growth cities with limited natural water resource.