There will always be companies that are obviously great investments -- in hindsight. Through the rearview mirror, we know we should have bought Microsoft or Wal-Mart at their IPOs, realizing astronomical returns over the years. Yet for every stock out there screaming "buy me," there are others that simply nudge us in the ribs and nod knowingly. They may be tomorrow's obviously great investments, but how do we tell them from the thousands of pretenders?

The stars' walk of fame
Over on our investor intelligence site, Motley Fool CAPS, we know these opportunities as four-star stocks. These companies rank higher than most of the other 5,000 stocks in the CAPS universe, but they're just shy of achieving stardom. In the long shadows of stocks sporting the coveted five-star rating are top-tier companies approaching greatness.

While the full "secret sauce" of how the ratings are calculated is kept proprietary, there are three factors that influence a stock's star rating:

  • Whether a stock is rated "outperform" or "underperform."
  • The length of time it is expected to perform (a few months or a few years).
  • The ratings of the investors who make the picks.

Every player is rated; so is every stock. The best and brightest players are considered All-Stars, and since they are correct more consistently than their peers, their opinions weigh more heavily on a stock's ratings.

Searching out of the spotlight
So while all the attention might be focused on the five-star stocks, good investments slip under the radar with only four stars. Yet we can sift through the CAPS database to find some of these four-star companies approaching greatness:

  • Akamai (NASDAQ:AKAM)
  • ClickSoftware (NASDAQ:CKSW)
  • ViroPharma (NASDAQ:VPHM)
  • Level 3 Communications (NASDAQ:LVLT)
  • Coeur D'Alene Mines (NYSE:CDE)

Some of the names you might find surprising. After all, doesn't everyone know about Internet content accelerator Akamai? Even The Motley Fool serves up content with its technology, and the company was recommended by Motley Fool Rule Breakers in 2005.

Sometimes, though, the most familiar names can provide some of the best investment opportunities, because we've forgotten about the potential they still hold. Just as importantly, the 65,000 investors on CAPS are giving these companies the nod as less obvious places to look for tomorrow's great buys. So let's delve into why these companies might merit your attention.

Digging for gold -- er, silver...
These long-term opportunities can earn you the greatest profits. Coeur D'Alene Mines burrows in the earth for silver, and with supplies getting scarce, silver prices could rise. You buy metals as a hedge against inflation, and with the Fed willing to risk such inflation to save the economy from recession, this might be a stock to buy. While we've heard that before about silver and its cousin gold, Coeur D'Alene has unique properties that may make it ripe for growth.

CAPS investor sam07 believes that the troubles the company faced earlier this year are now behind it, and that Coeur D'Alene has made strategic acquisitions to position it for the future:

CDE has taken a beating in the last few months, paying high premiums to replenish its silver reserves for the years to come and encountering environmental setbacks. Costs, increasing environmental concerns and rarity make it harder and more expensive to mine, for everybody in the industry. They've just been hit harder than their competitors this year; everything happened at the same time.

CDE is in a simple market: mine silver, sell silver. As long as they have silver, they have cashflow. The company is in place, the clients are there, the management is there. With the matter of the reserves settled for now, money will keep coming in. They didn't pay a premium for nothing; these reserves will be worth it in the long run.

CDE will within a few years emerge as the silver world leader. A metal for which there will always be demand. Wait for a good entry point. Undervalued stock right now but you might have it for even cheaper in the months to come ...

A great opportunity for you
That's the current word on Coeur D'Alene, but what are your thoughts? Are these four-star stocks still investment-grade material? On Motley Fool CAPS, you can give your input, which could ultimately influence how they're rated. Outperform or underperform, near-term or well into the future -- your opinion counts, and CAPS is totally free.

Akamai is a recommendation of Motley Fool Rule Breakers. Discover why the market-beating growth-stock service thinks this company deserves five stars with a free 30-day trial.

Fool contributor Rich Duprey owns shares of Wal-Mart, but does not have a financial position in any of the other stocks mentioned in this article. You can see his holdings here. Microsoft and Wal-Mart are recommendations of Motley Fool Inside Value. The Motley Fool has a disclosure policy.