Some companies are obviously great investments -- in hindsight. Yet for every stock out there screaming "buy me," others simply give us a nudge and a nod. How can we tell tomorrow's obviously great investments from the thousands of pretenders?

The stars' walk of fame
On Motley Fool CAPS, these opportunities can be found among our four-star stocks. In CAPS' proprietary ratings system, they rank higher than most of the other 5,400 rated companies, but they're just shy of superstardom. While all the attention might be focused on their five-star peers, we can sift through CAPS to find four-star companies approaching greatness. Here are a handful:

  • Clean Energy Fuels (Nasdaq: CLNE)
  • Freeport-McMoRan (NYSE: FCX)
  • Mechel (NYSE: MTL)
  • Healthways (Nasdaq: HWAY)
  • Nokia (NYSE: NOK)

Some of these names might surprise you. For example, Nokia is as well-known today for its cell phones as it once was for its cameras. Almost great? Even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold.

Billionaire oilman T. Boone Pickens can't be pleased with the environmental disaster unfolding in the Gulf of Mexico, but he has to be happy that his natural gas and wind plans might move closer to center stage as a result. While some natural gas incidents over the past few days show there are risks there as well, Clean Energy Fuels is building a network of natural gas fueling stations.

With Ford announcing it is developing natural gas and propane pickup trucks for fleet owners, the tipping point is coming for their proliferation. However, the 165,000-plus CAPS members chose these companies as less-obvious sources for tomorrow's great buys, so let's see why they might merit your attention.

In the sight of greatness?
Because of its many industrial and commercial uses, copper is closely correlated to production numbers. Prices had staged a pretty dramatic rise after hitting some of their lowest levels last year, but copper now trades at levels it hadn't visited in about eight months.

Freeport-McMoRan's Grasberg mine in Indonesia is the world's biggest copper and gold mine in terms of reserves, so its fortunes would also closely correlate to global demand. While the immediate financial concerns in Europe, as well China possibly applying the brakes on its own development, mean investors should be cautious, the longer-term outlook remains strong. Moreover, as highly rated CAPS All-Star TSIF notes, copper and gold often work at cross purposes, so while copper is down now, gold is hitting record highs.

Freeport-McMoRan Copper and Gold is certainly not a boring stock in a [volatile] market. It swings with the economy in a mixed up direction, since [its] two core components, copper and gold, often work out of sync with each other. If the markets go defensive and want gold then it should offset any associated decrease in copper. 

On the shoulders of giants
I'm not sure I'd listen to those who say that demand hasn't been a problem for the steel industry, or that China will build us out of the recession. While some report that steel producers reduced capacity and reduced inventories, leaving themselves open to problems in meeting customer demand, BHP Billiton (NYSE: BHP) and Rio Tinto are now moving to monthly pricing contracts and hiking prices by as much as 23% in some markets.

China Daily reports that steel producers are headed for hard times because their costs are rising. The country's largest steelmaker, Baosteel, was forced to cut prices to offset falling demand, and analysts are seeing demand drying up further down the chain in autos, shipping, appliances, and even housing.

As with the copper situation, though, the short-term issues may be worrisome, but the longer-term outlook is one of growth. Management for Russian steelmaker Mechel obviously sees that, recently opening an office in China to expand its presence there. CAPS All-Star BudandMolly writes that China and other emerging economies will still be the growth centers.

Long term pick. Coking coal production and steel will be back in high demand as third world countries recover from this recession.

A big opportunity?
Healthways might be insulated from the vagaries of commodities markets, but not the whims of politicians. Things are uncertain for the company, which provides wellness programs, because there's no telling if its business will grow under health-care reform. And its domestic earnings guidance is still below 2009's lackluster results. On the international side, though, things look much better, with Healthways expecting to break even or even report a slight profit -- much better than 2009's $0.11 per-share loss.

Investors seem to think it will be a healthy year, with 95% of the more than 400 CAPS members rating the company picking it to outperform the market. Visit the Healthways CAPS page and let us know what you think.

A great opportunity for you
Investor sentiment suggests these four-star investments still seem to be on their way to five-star greatness, but it pays to start your own research on these stocks on Motley Fool CAPS. Read a company's financial reports, scrutinize key data and charts, and examine the comments your fellow investors have made, all from a stock's CAPS page.

Sign up today for the completely free service and let us hear what you have to say about the great and almost-great companies that interest you.

Nokia is a Motley Fool Inside Value recommendation. Ford Motor and Healthways are Motley Fool Stock Advisor selections. Try any of our Foolish newsletter services today, free for 30 days.

Fool contributor Rich Duprey does not have a financial position in any of the stocks mentioned in this article. You can see his holdings. The Motley Fool has a gold-plated disclosure policy.