Drowned out as it was by the hullabaloo of other news, you may not have noticed, but on Monday the Institute for Supply Management released its latest monthly report on the state of the American economy:

The good news is that we're still growing. For the 21st consecutive month, manufacturing activity expanded in America. Even better, that growth is spreading out to all corners of the economy. Over the weekend, Warren Buffett confided that from what he's seeing at the 80-odd subsidiaries that make up Berkshire Hathaway (NYSE: BRK-A) (NYSE: BRK-B), the economy is still ... slowly ... improving. ISM confirms this: "Of the 18 manufacturing industries, 17 are reporting growth in April."

The four industries doing best are: wood products, plastics and rubber products, primary metals, and transportation equipment. Which tells us one thing we already knew -- that Ford (NYSE: F) and General Motors (NYSE: GM) are selling a lot of cars lately. And one thing we didn't -- that somebody, somewhere, is buying lumber.

Could it be time to invest in Plum Creek Timber (NYSE: PCL) perhaps? American Woodmark (Nasdaq: AMWD)? Or is it even possible that -- gasp! -- housing could be turning around? Add a few housing stocks to your Motley Fool Watchlist and find out.

Foolish final thought
Monday's Wall Street Journal contained a curious note to the effect that futures prices on several key commodities -- zinc, lead, and cotton among them -- have begun dropping. If this is a new trend, it will be very happy news for many manufacturers. It will boost profits at Ford and GM, for example, by driving down the costs of vehicle batteries (for electric cars, and otherwise). Similarly, lower cotton prices would help at least one Berkshire business -- Fruit of the Loom -- and come at a very convenient time for Under Armour (NYSE: UA), which is launching a new line of cotton sports apparel. On the other hand, this price swing must be a very recent development. Because as of April, ISM was still stating that "no commodities are reported down in price."

Tread warily, watch carefully. And stay tuned to the Fool as we continue to track these trends.