Love him or hate him, you've got to admit that Jim Cramer, CNBC stock commentator and co-founder of (NASDAQ:TSCM), is a pretty interesting guy. We've written about him many times here in Fooldom, where he has his share of admirers:

Well, Cramer himself recently wrote about exchange-traded funds (ETFs), those stock-like, fund-like investments, and he made a lot of sense. Mostly. Permit me to share some of his thoughts -- and mine.

For starters, he noted that the Claymore Group is issuing an ETF designed to track stocks that have little or no coverage among Wall Street analysts and that it's looking into an ETF that focuses on companies with significant insider buying. To him, these represent "the latest in the out-of-control creation of ETFs that's been going on lately." I agree on that front, having asked, in April, "Are ETFs Out of Control?"

Cramer went on: "[T]hese instruments are now taking on all aspects of stupidity. The idea of picking undercovered companies and buying them makes no sense at all. The idea of buying good undercovered companies makes sense. The idea of buying companies where there is insider buying makes no sense. The idea of buying good companies where there is insider buying, well, that I can get with."

These are good points. After all, Tom Gardner has had great success investing in smallish, little-followed companies in his Motley Fool Hidden Gems newsletter. As a healthy and growing company begins to get noticed and written about positively, its stock is likely to advance on the new awareness.

Cramer mused on some possible ETFs in the offing: "I would not be surprised to see an ETF of all ETFs. Or a best-of-ETFs ETF. . How about an ETF that just owns stocks that start with the letter P?"

He concluded by recommending something that we here at The Motley Fool have been recommending for a long time: index funds, which you can invest in via ETFs, as well as through the funds themselves. "The only ETF worth owning," Cramer said, "is one that is an index fund to a big index for diversification, and if I want that, I would go with Vanguard's mutual funds: low fees, good execution."

I agree with that in part. For many people, index funds are all they need. But for those who want to try topping the market's average -- those with some time to do some learning and choosing -- some other ETFs could make sense, as could some carefully selected mutual funds and stocks.

For example, you can get instant exposure to many of the world's emerging markets via the Vanguard Emerging Markets ETF (AMEX:VWO), which is invested in South Korea's Samsung, Israel's Teva Pharmaceuticals (NASDAQ:TEVA), Brazil's Petroleo Brasileiro (NYSE:PBR), Hong Kong's China Mobile (NYSE:CHL), India's Infosys (NASDAQ:INFY), and Mexico's Cemex (NYSE:CX).

Learn much more in our ETF Center. It features info on how ETFs stack up against mutual funds, how to develop an investment strategy with ETFs, how to avoid pitfalls, and how to steer clear of ETF imposters.

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Longtime Fool contributor Selena Maranjian owns shares of the Vanguard Emerging Markets Mutual Fund. The Motley Fool has a disclosure policy.