Last year, Wynn Resorts CEO Steve Wynn was spending two hours each day on Chinese lessons. At age 65, Wynn is worth $3.9 billion -- yet he's still learning new tricks.

Why? Because the Wynn Macau -- Mr. Wynn's latest megacasino -- was getting set to open just off the coast of China. That's right on the doorstep of some 3 billion potential customers.

Big bets for big paydays
How has the Wynn Macau fared? Analysts see it tracking above previous estimates, and contributing some $300 million in EBITDA in 2007.

But Steve Wynn isn't the only billionaire going gaga over foreign markets. Wynn rival and Las Vegas Sands CEO Sheldon Adelson, himself worth $28 billion, is making a similar investment in Macau's potential. Then there's the large number of companies, from Orbitz Worldwide  (NYSE:OWW) to Tyco Electronics (NYSE:TEL) to Helmerich & Payne (NYSE:HP) to (NASDAQ:PCLN), whose recent earnings reports showed strength overseas. As economist Joseph Carson told The Wall Street Journal recently, "The international influence on firms' profits has never been so strong."

Entrepreneurs and investors alike
Meanwhile, there are the master investors who have been buying up foreign stocks at a rapid clip. Mason Hawkins recently bought Korea's SK Telecom (NYSE:SKM) and Chris Davis picked up shares of Ireland's Ryanair (NASDAQ:RYAAY).

Even Warren Buffett stoked the international frenzy early in 2006, with purchases of PetroChina (now sold) and Israel's Iscar Metalworking.

The question we need to ask
So -- and you had to know I was coming around to this -- what have you been adding to your portfolio lately?

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This article was originally published on Jan. 19, 2007. It has been updated.

Tim Hanson owns shares of Wynn Resorts. is a Motley Fool Stock Advisor recommendation. No Fool is too cool for disclosure.