Observations of an old lady sitting on the Pacific rim:
China's demand for steel and cement should back off a little once they are in the finish-out phase of prepping for the Olympics. On the west coast a breather from those prices would be much appreciated. However, long term, the demand for those commodities by China will not abate. One activity that put substantial supply of rolled steel on the market 5 to 10 years ago was the scraping of old ships (most go to India). I think that cycle has peaked. With the increase in global trade the demand for ship construction has increased, and there is construction boom on the Pacific rim. Notice that a Russian firm wants to buy an Oregon steel firm?
So, if your commodity of interest is steel or cement I think you are good for the long term.
Oil prices have gone down from insane to ridiculous (mild winter?!), but they are not about to get reasonable. The one element in the oil company mix is the workout of contracts with Russia and political instability. The oil business should continue to be profitable, those with reliable crude contracts just about print money.
Composites are replacing aluminum in airplanes (yet to see how composites hold up long term), so firms like Alcoa need to adjust their product mix - bauxite prices may be under pressure.
Lumber prices have gone down because of slackening new home construction, so standing timber prices will go down. China doesn't seem to use lumber for construction (warm climates, termites/dry rot?).
Silver, gold - no opinion but gold seems to correlate with uncertainty.
So... WHY THE HEY DID THE MARKET BACK OFF SO MUCH THIS AFTERNOON?