After being blamed in the past for artificially pushing grain prices to very high levels, index funds have pretty much slipped away from public attention these days. However, they are still in business.Commodity price indices are an easy and convenient way to track the general direction of a broad range of commodities. They also facilitate researching the history of price trends for commodities. Typically, a commodity price index will track futures market prices for a group of important commodities from the energy sector, industrial and precious metals as well as agricultural crops and products. Individual commodities are usually given different weights within the index, based on what is seen as their relative importance. Futures market pri...