Any time a new type of asset reaches the top of the performance charts, it's only a matter of time before the bandwagon starts rolling. In today's fast-moving financial world, in which financial services companies are constantly searching for the next great innovation in trading strategies and investment vehicles, the lag time between when an asset class becomes popular and when huge product offerings start rolling out has compressed as much as securities regulators will allow.

It wasn't that long ago when there were only a few ways in which most people could invest. Individual stocks and mutual funds were relatively easy to buy, as were a few fixed-income investments like savings bonds and bank certificates of deposit. There were also more complicated investments, including futures contracts, options, and various forms of private investment options such as real estate limited partnerships and energy trusts. But these investments were typically reserved for people with high net worth who could afford to take substantial risks with their money and who could obtain professional advice about whether it made sense for them to add these investments to their overall portfolios. It was considered necessary to protect ordinary investors from themselves by restricting access to the wider universe of available investment alternatives.

These days, the floodgates have opened to the average investor. With the advent of exchange-traded funds, you can find custom-made investments that allow you to participate in nearly any market you can imagine. Want to invest in the Japanese stock market? There's an ETF for that: iShares MSCI Japan Fund (AMEX:EWJ). Would you prefer a basket of utility stocks from around the world? Try the S&P Global Utilities Fund (AMEX:JXI). ETFs are making it possible for anyone with a standard brokerage account to go well beyond the traditional world of stocks and invest in nearly anything.

In addition to that, it's now possible for investors of relatively modest means to gain entry into areas that were formerly reserved for the upper echelons of a financial institution's clientele. Opening an account that allows you to trade futures and options is as easy as opening an online stock brokerage account. Meanwhile, some stockbrokers are inviting their customers into the world of private equity, direct lender financing, and hedge funds. It's enough to make you wonder: How did people manage to invest before without all these choices?

The latest hot sector
Think about commodities for a moment. Prices of many commodities have been on a roll lately, with precious metals approaching or exceeding levels last seen during the inflationary period of the late 1970s and early 1980s. Crude oil and gasoline prices have hit all-time highs. As the U.S. dollar began a precipitous decline in value against other major currencies a couple of years ago, many professional investors looked at commodities as a way to hedge against currency risk and perceived fiscal problems within the American economy.

In response, you can see all the new ways that investors can try to claim their piece of these huge returns. For those who want to buy gold or silver but not have to worry about where to stash valuable coins or a bulky bullion bar, ETFs like the StreetTracks Gold Fund (NYSE:GLD) and the iShares Silver Trust (AMEX:SLV) give investors ownership of the equivalent of a tenth of an ounce of gold or 10 ounces of silver, respectively. Mutual funds like the PIMCO Commodity Real Return Strategy Fund use a combination of derivatives and fixed-income securities to match the return of popular commodities indices, such as the Dow Jones Commodity Total Return index. Deep-discount brokerage firms like Interactive Brokers give many investors direct access to agricultural, energy, precious metals, and financial futures contracts.

The fundamental things apply...
Even before these new alternatives became available, there were ways to make money in commodities. For precious metals investors, the stock prices of mining companies like Newmont Mining (NYSE:NEM) or Coeur d'Alene (NYSE:CDE) often move roughly in line with the price of gold and silver. Energy investors could use the stocks of drillers like GlobalSantaFe (NYSE:GSF), producers like Chevron (NYSE:CVX), or refiners like Valero (NYSE:VLO) as proxies for the price of crude oil or natural gas. People interested in agricultural products could look to producers like Monsanto (NYSE:MON) for profits. For investors who are more comfortable with company stocks as investments, the opportunities to make money from trends in other markets have usually been available in the stock market.

However, investing in companies brings its own risks. Some investors like these new ways to invest in the commodities market because they allow you to focus entirely on the commodity itself. If company management doesn't think the way you do, you may find yourself frustrated by stock prices that don't move the way you want. For instance, when gold prices started to rise, not all gold miners followed suit. This is because many miners had already locked in low prices on future production, causing them to miss out on the benefits of rising prices in the cash metals market. Miners that retained their exposure to price movements, on the other hand, generally did very well. Investing directly in commodities avoids the extra work of monitoring your company's actions and their effect on the stock.

Fads come and go
Investing in commodities isn't necessarily such a terrible thing. To the extent that commodity prices move independently of stock and bond prices, commodities may actually add to the benefits of diversifying your portfolio. Yet you should keep in mind that with commodity prices at high current levels, now may not be the best time to buy. While the availability of new products may make it easier to invest, consider that in the past, new investments in trendy sectors often came at the worst possible time. As proof, one need look no further than the numerous Internet-sector mutual funds that appeared in 1999 and 2000, just in time to see Internet stocks peak and plummet. As with any new product, the best rule of thumb is "let the buyer beware."

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Understanding the revolution in new financial products is important when you're trying to save for retirement. For help in learning about your options, look to the Motley Fool's Rule Your Retirement newsletter. Foolish expert Robert Brokamp examines ETFs, commodities funds, and all sorts of other investments to help you find what will work best for you. Take a free look today.

Fool contributor Dan Caplinger is one of those weird people who actually enjoys figuring out how new financial products work. He doesn't own shares of any of the companies mentioned in this article. The Fool's disclosure policy is a hot commodity.