With worries about the weakening value of the dollar, people are continually asking Clark if they should take everything they've got and put it into gold. In general, the consumer champ only recommends putting five or 10 percent of your overall portfolio into gold or other precious metals.

But buying actual bars of gold is not recommended. Why? Storage can be cumbersome and there's a huge spread on the buy and the sell. That's why Clark's preferred way for you to own gold is through a gold exchange-traded fund (ETF).

ETFs are the fastest growing area of investing, and the penny-pincher likes to call them "a mutual fund for the next era." You buy ETFs exactly like you would a stock -- preferably through a zero-commission broker -- and you can sell them at any time.

With a gold ETF, you let the fund store the physical bars of gold at minimal cost to you. And then you can buy and sell at will, without worrying about getting clobbered on the spread. Below are some ETFs that let you invest in gold or precious metals.

• Fidelity's PowerShares DB Precious Metals Fund

• iShares COMEX Gold Trust

• Central Fund of Canada

• Central Gold Trust