If you are interested in trading you would probably want to learn more not only about Forex Brokers but also about Commodity Brokers. Commodity Broker is a company who executes clients orders to buy or sell commodity contracts on their behalf.
In past Commodity Brokers bought and sold grain and livestock futures contracts. Then they mainly traded derivatives based on basic commodities and primary products such as metals, gas, oil, energy and agricultural goods.
There is a great number of online Commodity Brokers. Choosing one to deal with pay attention at his reputation and learn if it is supervised by any regulatory authority (such as Commodity Futures Trading Commission and National Futures Association in US) in order to lower risks and avoid unnecessary problems.