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 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 that might become great.

  • Conseco (NYSE:CNO)
  • Energy Conversion Devices (NASDAQ:ENER)
  • ExxonMobil (NYSE:XOM)
  • US Bancorp (NYSE:USB)
  • Verizon (NYSE:VZ)

Some of these names might surprise you. While some financial institutions have been shaken to their very foundations, others like US Bancorp still have winning ways. Almost great? Even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold. However, some of the 135,000-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?
Beyond going on a "production hiatus" and using furloughs to bring significant savings, solar company Energy Conversion Devices still hopes President Obama's plan to spend $150 billion on energy will eventually stimulate demand for its integrated photovoltaic roofing systems. Collapsing polysilicon prices have really hurt the margins of Energy Conversion Devices, MEMC Electronic Devices (NYSE:WFR), and others that have had to lower prices on their products. But that serves to clear out higher-cost inventories in advance of the price hikes expected in the industry sometime next year.

That positioning is evident in Energy Conversion Devices' recent purchase of Solar Integrated Technologies, a maker of photovoltaic (PV) systems for commercial buildings, and a deal with Warren Buffett's Johns Manville to supply its UNI-SOLAR laminates for commercial roofs. The Berkshire Hathaway company manufactures energy-efficient building supplies, and this marks its first foray into solar energy. The agreement also lets Energy Conversion Devices in on Johns Manville's extended and diverse network of customers.

CAPS member pradsynair says the company's offerings are a competitive advantage.

They have several high quality products in the pipeline and Obama's push to greener technology is definitely going to help ENER. They build solar cells as well as batteries that fuel hybrid cars among others. One of the analysts knocked the wind out of ENER's sail by suggesting a price of $13. But J.P Morgan is going to come up with its expectation shortly and that will definitely be in the $16-$18 range.

Bouncing back
Shares of Indiana-based life insurer Conseco started doubling in value over the past quarter, just as it was identified as a formerly cold stock that was heating up. It is expecting to report its second consecutive profitable quarter, based on the strength of its Banker's Life business and lower investment losses. Apparently, the market's rally since March has helped bolster the insurer, which will release earnings Tuesday.

Yet there is still a cloud over Conseco. While the insurer is expected to report that it was complying with all terms of its debt agreements as of June 30, earlier this year it warned that it might default on its credit facility if there were a "going concern" letter from auditors. It was able to renegotiate terms, easing worries, but its continuing tight capital position means it's not out of the woods yet.

CAPS member zoulou12 recognizes those risks, but figures the rewards will be substantial for investors willing to stick it out with Conseco.

High risk play, with refinancing issues but potentially 5 or 10 bagger once the issues are solved. The stock will stay under pressure near term and be very volatile. Cash and cash flow to be watched closely.

Good risk/reward play but not for faint heart investors.

Few insurers of any stripe -- health, life, or even property and casualty -- have performed as well as Conseco during the past three months. Not Aflac (NYSE:AFL), Prudential, or Aetna. In fact, the 178 companies in the CAPS Insurance sector have returned an average of just 9% over the past 30 days.

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.

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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. The Motley Fool has a gold-plated disclosure policy.