Taser (NASDAQ:TASR) is a stock on a run. Last Friday, I wrote that this stock had increased 69-fold since New Year's Eve 2002. Well, let's update that one trading day. The stock is up 82-fold since the champagne was iced to celebrate the arrival of 2003.

The news sending the stock climbing 20% today is the U.S. Department of Homeland Security's approval of an international airline's use of the nonlethal devices on its flights to and from the U.S. Ah, another market opens.

It wasn't too many months ago that Dow Jones' (NYSE:DJ) Barron's was questioning the stock's valuation based on the market potential for its devices in the U.S. While the core police business has its limits, large orders continue to roll in, and the company continues to enjoy stunning triple-digit revenue and earnings growth.

The market in the U.S. is expanding too. First, there's the new personal protection device that brings the new small-format Taser technology to the average person. Second, there is the U.S. military, which is using the devices in Iraq.

As markets expand, so do the opportunities. The company recently announced a rifle mounting system to support military applications; it will now be marketed in the U.S. to police SWAT teams.

Don't overlook international markets, either. The use of Taser devices by law enforcement officers has been approved in the United Kingdom, Finland, and Sweden.

The company's active research operation includes a longer-range, nontethered device, and its joint venture with General Dynamics (NYSE:GD) recently demonstrated an anti-personnel munition for use in military-area denial.

The company has also taken on critics such as Viacom's (NYSE:VIA) CBS, which has questioned whether the device is nonlethal. Evidence continues to mount that the weapons perform as advertised.

What supports Taser's stock is its high 48% operating margin (which is a result of no real competition in the marketplace). Consider, too, that margin dwarfs those at companies with lighter business models such as Coca-Cola (NYSE:KO), Microsoft (NASDAQ:MSFT), and Motley Fool Stock Advisor recommendation Marvel Enterprises (NYSE:MVL).

The stock has been on a roller coaster ride -- as this one-year chart shows. While 14% below its all-time high, it currently trades for 58 times 2005 analyst estimates. While there are positive business fundamentals at work here, there is also an extremely large short position. The combination causes the stock to jerk up and down like a suspect shot with a Taser.

Fool contributor W.D. Crotty owns stock in Marvel but none of the other companies mentioned.