Fools may not be that familiar with insurer Aflac (NYSE:AFL), but they're probably well aware of its duck mascot, famous for starring in commercials with Yogi Berra and uttering the company name. However, talking ducks aside, the stock is worth getting to know as well.

Aflac offers supplemental health and life insurance, selling products that cover an individual's hospital stays or general medical expenses. Speaking of Japan, most of Aflac's sales stem from that country (74% for 2005), with the rest of operations residing back home in the U.S.

Because of the significant amount of business in Japan, currency fluctuations between the yen and the U.S. dollar greatly affect reported results. When the yen is weak, sales and earnings suffer when translated back to the United States. However, the company notes that it isn't actually converting yen into dollars, but has to do so for financial reporting purposes. Overall, the driving factors for Aflac's stock are market conditions in Japan and related currency fluctuations.

The stock is trading down today, ever since the market expressed concern about intense competition in Japan. In yesterday's press release, management stated that this competition hurt second-quarter sales and is expected to weaken results for the rest of the year.

Operating earnings per diluted share for the quarter increased 17.2%, but if you ignore the weaker yen, they were up 20.3%. It's also worth noting that management makes certain adjustments to GAAP income to get to operating earnings, such as recently removing realized gains from a bond-swap program or fair value of currency swaps. Any way investors choose to slice it, earnings growth was strong, even though sales grew only about 3%, and management continues to actively repurchase its stock.

Aflac has a stellar track record of growth that can be expected to continue going forward. Its products have universal appeal as a way for individuals to obtain further insurance coverage, filling in the gaps where traditional private or governmental insurance may be lacking. Because of an aging population in the U.S. and Japan, medical needs will only increase, and rising health-care costs could enhance the appeal of supplemental offerings. In the longer term, there appears to be plenty of growth remaining in the U.S and Japan, but down the road, Aflac has the rest of the world to consider for expansion opportunities.

UnumProvident (NYSE:UNM) is a key domestic competitor, as are Conseco (NYSE:CNO) and Delphi Financial (NYSE:DFG). Or take your pick from more than 2,000 life insurance companies, including behemoths such as AIG (NYSE:AIG) or MetLife (NYSE:MET).

Overall, a trailing P/E multiple of just under 15 -- for a company that has grown earnings more than 18% annually for at least the past five years -- looks compelling to me. Profit margins are high, as are returns on equity and capital, and operating cash flow has been at least three times greater than reported net income for the past three years. Similar to a number of large-cap market leaders, the valuation is at a five-year low. After doing their own due diligence, Fools may want to embrace the duck.

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Fool contributor Ryan Fuhrmann is long shares of AFL, but has no financial interest in any other company mentioned. The Fool has an ironclad disclosure policy. Feel free to email him with feedback or to discuss any companies mentioned further.