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 5,300 starred 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 firms approaching greatness. Here are a handful of four-star firms approaching greatness.

  • Energy Conversion Devices (NASDAQ:ENER)
  • Excel Maritime (NYSE:EXM)
  • Halliburton (NYSE:HAL)
  • ION Geophysical (NYSE:IO)
  • Sequenom (NASDAQ:SQNM)

Some of these names might surprise you. After all, oil fields expert Halliburton has been an industry leader for 80 years. Almost great? Even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold. However, the 145,000-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?
How big will China's growth be next year? If you listen to economists, the laws of supply and demand, particularly regarding monetary policy, don't apply when it comes to China. It seems as though, while the nation is flush with capital, every bit of stimulus spending is still benefiting the economy. Where such "free money" causes investment dislocations here at home, the Chinese appear to have figured out how to work around such impediments. Some analysts now expect China's economy to grow by 10% in 2010.

Iron ore imports by China were one reason for analyst enthusiasm. They increased by 12% in November alone, and expected contract prices for iron ore may rise 15% to 20% this year to the second-highest rates on record. Look for dry bulk shippers like Excel Maritime and DryShips (NASDAQ:DRYS) to similarly benefit from rising expectations.

But investors would be wise to use caution. Even though it looks like China can invest with targeted precision in its economy with no ill effects, the reality is that there is dislocation occurring -- and asset bubbles could be forming. Real estate speculation is booming, and the Shanghai stock market rose 75% last year. If price inflation takes root (it rose 0.6% in November, the first price rise in nine months), the government may have to take strict measures to keep it under control.

At least for the meantime, investors are counting on shipping to continue improving. hittmiss1 is counting on better economic times to keep Excel Maritime shipshape.

Fully 96% of the more than 1,800 CAPS members rating the dry bulk shipper expect it to outperform the market. Why not head over to the Excel Maritime CAPS page and discuss the potential for China to sink this sector?

Try this on for size
With ExxonMobil (NYSE:XOM) making a bold move into natural gas, it's a safe bet that the company believes there's a lot of opportunity for exploiting existing deposits and discovering new ones. For companies that service the oil and gas industry, this should mean greater investment all around. ION Geophysical in particular ought to gain, as it generates diagrams of crude oil and natural gas deposits for exploration companies.

A joint venture deal with the world's largest land seismic contractor back in October gave ION a nice influx of cash while allowing it to cut its debt load. CAPS member drsamsnake says the need for further exploration gives ION the impetus to grow, while being in an out-of-favor industry lets investors in at a cut-rate price:

Out of favor as people look to green, but we need oil and gas at least for the next half century as other sources of energy ramp up. And guess who will help us to find it. Good cash flow, heavy debt, but the excessive depression of the stock will help to slingshot it forward in the years to come.

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.

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