I like to keep track of what it currently costs for a barrel of oil. Prices constantly go up and down, and I like to see what may have caused it to spike or drop.
http://www.oil-price.net is a very interesting website that is very informative. It has articles that talk about why prices fluctuate.
http://www.nymex.com/index.aspx allows you to see what are the prices for the various commodities. These include metals and gasoline.
Since I do not know much about how the market works, I like to read these type of articles.