We normally think of the world's tax havens as countries with low tax rates and laissez-faire regulation. But there are also many tax havens within countries.

Take Zug, Switzerland. Some 25,000 companies have set up shop in this quaint Alpine town, which is just 40 minutes south of Zurich by train. About 55 commodity-trading firms, many of them among the world's largest, operate in Zug. Along with Chicago, Geneva, and London, Zug is where many of the world's commodities such as oil, metals, and grains get bought and sold.

Why Zug? Aside from the town's proximity to Zurich, there are two reasons: low, low taxes and deep talent, according to Simion Casey and Saijael Kishan of Bloomberg Markets magazine (story not available online).

Zug is popular with trading companies because it's full of experienced people who at some stage have worked for Phillip Brothers, Marc Rich, Glencore, and other commodity-trading companies," says Hans Jörg Brun, chief executive officer of Marc Rich Holding GmbH, the Zug-based holding company of former commodities trader Marc Rich. "This includes even secretaries and switchboard operators."

Sales at Zug's Ferrari dealership went up 190 percent in 2006, so things must be going well.