By making American products cheaper for most foreign buyers, the dollar is helping many U.S. companies boost their overseas sales. The weakening dollar also gives domestic businesses a competitive edge at home, making their products cheaper than rival imports.

The greenback's value slipped for a fourth straight day Thursday, to its lowest level in more than a year against other major currencies. It now takes $1.49 to buy one euro, compared with $1.26 seven months ago. Many experts expect the dollar to keep falling in the coming months.

That decline has its downside, making imports including commodities like oil more expensive for U.S. businesses and consumers. The price of crude rose to $77.58 a barrel Thursday, a nearly one-year high that's due at least in part to the slumping dollar.

But to companies like Paulson Manufacturing Corp. in Temecula, Calif., which makes goggles and other protective gear, the greenback's slide is good news.

For a customer in Brazil, the company's top overseas market, buying $10,000 of Paulson's face shields in early March meant shelling out more than 24,000 Brazilian reals. That same order costs only about 17,000 reals now.

"It certainly helps to have the dollar go down," said owner Roy Paulson, who's considering expanding his staff of 135. "I'll have more exports. There's no doubt about it."

Even U.S. companies that don't sell any products abroad can benefit from the fading U.S. currency.

The U.S. tourism industry, including hotels, restaurants and stores, could see a bump in business from foreigners sleeping and eating and shopping at what may seem like bargain prices to them.

Tour operator RMP Travel in New York is getting more requests for quotes from overseas travelers interested in visiting the United States.

"It looks like 2010 could be promising," said Suzi Steiger, the company's president.

U.S.-based multinational firms are likely to cash in on the humbler greenback as well. The reason: About 40 percent of sales by companies in the Standard & Poor's 500 stock index are made overseas. So when Procter & Gamble, Walt Disney and Abbott Laboratories convert money made in euros or Japanese yen into dollars, they will see more dollars on the bottom line.

That expectation is one driver of the rally on Wall Street that took the Dow Jones industrials back above 10,000 points this week.

The sinking dollar comes with some immediate downsides, of course.