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 their five-star peers get all of the attention, we can sift through CAPS to find four-star companies approaching greatness. Here are a handful of them.

  • Garmin (NASDAQ:GRMN)
  • Vulcan Materials (NYSE:VMC)
  • Textron (NYSE:TXT)
  • Sonus Networks (NASDAQ:SONS)
  • Marsh & McLennan (NYSE:MMC)

Some of these names might surprise you. GPS maker Garmin, for example, has been helping drivers and investors find their way for 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 135,000-plus CAPS members chose these companies as less obvious sources for tomorrow's great buys, so let's see why these picks might merit your attention.

In the sight of greatness?
With the decline of Nortel Networks, the telecom industry is going to become a smaller, fiercer market. Nokia Siemens Networks is purchasing the wireless assets of Nortel for $650 million, while Nortel looks for buyers for its optical networks, security products, and unified communication-solutions properties.

Nokia Siemens is signaling a much more aggressive stance for business in North America, a stance that must be a concern to Alcatel-Lucent (NYSE:ALU) and Sonus Networks. The latter reported that first-quarter revenues had fallen by 44% as it posted losses for the third straight quarter. Last month, it reiterated its guidance that full-year revenues would be significantly lower than what it had been last year.

Yet even though the competition will be tough, Sonus has a lot going for it that Nortel did not. For one thing, it hasn't been gripped by the desire to become the next Cisco (NASDAQ:CSCO). It's made only a handful of acquisitions over the past decade, and though it has recorded losses recently, it has more than $336 million in cash and short-term investments available to it. But equally important, it has no long-term debt.

Nortel's demise could very well be a gain for Sonus if it can snap up its VoIP and switching assets. Considering the stockpile of cash it has, that would be a strategic buy. But with the company repositioning itself under the leadership of its new CEO, it needs to show that its management team is not distracted. To some, the exit of two executives last year may make it look as if there's a veritable revolving door in the executive suite. Further, the climate for corporate tech spending is going to require that any purchases Sonus might consider be targeted for growth areas. Such spending initiatives slowed to 8% in 2008 but are expected to fall by 3% this year. Goldman Sachs, however, expects tech spending to fall 9% this year, but only 1% next year.

With its corporate restructuring, strong cash position, and little debt to weigh it down, Sonus Networks looks sufficiently fortified to weather the current economic storms. Highly rated All-Star CAPS member NicklesDimes figured earlier this year that the company was positioned to make some gains over the ensuing months, but the volatility of the market caused him to hedge his bets.

That wasn't such a bad call after all, because although Sonus' shares bloomed in May, they gave back the all the gains and then some this month. 

As part of the larger CAPS Communications Equipment sector tag, Sonus surpasses the average three-star rating of the industry, but it fell well below that benchmark in terms of performance. The 150 companies in the CAPS universe comprising the tag have risen more than 4% over the past month, but Sonus has fallen by more than 21% over that same time period.

A great opportunity for you
These four-star investments seem to be on their way to five-star greatness, and 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's hear what you have to say about the great -- and almost great -- companies that interest you.

Marsh & McLennan and Vulcan Materials are Motley Fool Inside Value recommendations. Garmin is a Motley Fool Global Gains pick. Try any of our Foolish newsletter services free for 30 days.

Fool contributor Rich Duprey has no 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.