The weak dollar has generated plenty of political debate, as well as some economic disagreement about whether it is good or bad.

Motley Fool Global Gains lead advisor Bill Mann points out that the weak dollar makes U.S. goods cheaper for foreign buyers, giving a lift to a variety of companies, from eBay (Nasdaq: EBAY) to Boeing (NYSE: BA). Fool Morgan Housel counters that we are net losers from a weak dollar because "We buy a lot more 'stuff' overseas than we export there, to the tune of nearly $2 billion every single day."

Of course they are both right, to some extent. According to the U.S. Census Bureau, "Total March exports of $148.5 billion and imports of $206.7 billion resulted in a goods and services deficit of $58.2 billion, down from $61.7 billion in February, revised." Econoday had pegged the consensus estimate at a $60.8 billion deficit. So, while we remain net losers today, we are catching up.

I want investment ideas
More important for me as an investor, though, is to figure out the best way to profit from the theme. Luckily, the Census Bureau report can help me do that. In a supplemental table, the report shows how broad categories of goods are affecting the total balance of trade.

The area that immediately jumps out to me is "food, feeds and beverages." In the first three months of 2007 we exported $18 billion worth of food and imported $20 billion -- a $2 billion deficit. For the same period in 2008 we exported $27 billion and imported $21 -- a $6 billion surplus.

The next step is to find out which companies are the biggest beneficiaries of that shift in trade imbalance.

Another table points specifically to "food and live animals." I was surprised to find that the trade balance for beverages and tobacco actually worsened in March, ruling out companies including Coca-Cola (NYSE: KO) and Altria (NYSE: MO), which I thought would benefit. This is one reason why it is important to look into the data and not jump to conclusions.

Room to run
Furthermore, I'm nervous. So many of the agriculture plays have already had large gains. With this in mind, I used Zack's Research Wizard to run a screen for food companies with increasing earnings estimates and moderate 12-month returns. I found three that could be worth further investigation.

Corn Products International (NYSE: CPO) makes the high-fructose corn syrup we find in so many products. According to its latest 10-K, sales outside North America represented 39% of total 2007 revenue. While consensus Wall Street earnings estimates for both 2008 and 2009 have risen sharply, only recently has the stock begun to separate itself from the pack.

Ketchup king H.J. Heinz (NYSE: HNZ) stock has barely budged over the last year, despite analysts ticking up their estimates by a few cents in the last 90 days. Its 10-K shows that 52% of its sales are generated outside North America.

Last but not least, there's Tyson Foods (NYSE: TSN). The stock of this livestock producer is actually down more than 15% over the last year. Meanwhile, the same group of analysts who three months ago were expecting the company to earn $0.26 per share this year and $0.89 next year, now expect the company to make $0.37 in 2008 and $1.15 in 2009.

Unfortunately, export sales of $2.7 billion were just 10% of total revenue. However, that could be changing. When the latest quarterly earnings were reported, the company said, "Our chicken and pork exports continue to be strong, and we are moving forward with our strategy for international expansion."

I hope you can see why I like to leave the political arguments to others. I'm too busy skimming through the data to find good stock ideas!

Want more?

Heinz is a Motley Fool Income Investor selection. Coca-Cola is a Motley Fool Inside Value pick. eBay is a Motley Fool Stock Advisor recommendation. Try any of our Foolish newsletters free for 30 days.

Fool contributor William Trent holds no position in any companies mentioned above. Email him your questions, and he'll answer them in a future column. The Fool has a disclosure policy.