We all know companies that, in hindsight, would have been obviously great investments. Through the rearview mirror, we now know that we should have bought Starbucks and Wal-Mart at their IPOs and earned hundredfold returns over the years.

Yet for every stock out there screaming "buy me," others simply give us a nudge in the ribs and a knowing nod. They may be tomorrow's obviously great investments, but how can we pick the right ones from the thousands of pretenders?

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

While the full "secret sauce" of how the ratings are calculated is kept proprietary, three factors 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.

Both stocks and players get ratings. The best and brightest players are considered All-Stars, and since they are correct more consistently than their peers are, their opinions weigh more heavily in favor of (or against!) a stock.

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

  • Golden Star Resources (AMEX:GSS)
  • Finisar (NASDAQ:FNSR)
  • Sigma Designs (NASDAQ:SIGM)
  • Kongzhong (NASDAQ:KONG)
  • Frontline (NYSE:FRO)

Some of the names, you might find surprising. Frontline is a shipping-industry leader that some sharp Fools hope will be one of tomorrow's monster stocks, just as DryShips (NASDAQ:DRYS) has been. But sometimes, we find that the most familiar names can mean some of the best investment opportunities, because we have forgotten about the potential they still hold. Just as meaningfully, the 74,000 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.

Fool's gold or rich vein?
Denver-based gold miner Golden Star Resources has been something of a disappointment for investors, as operational difficulties and high costs hobble its Ghana and West African mines. Yet a new BIOX sulphide processing plant has finally been completed, and the company recently received assurances from Ghana's government to ensure an investor-friendly environment. CAPS players seem to think a ramp-up in production might finally bring a shine to the miner's share price.

Nearly 400 CAPS investors have weighed in on Golden Star, and 96% believe it will outperform the market over time. CAPS All-Star nispe, with a 95.77 player rating, notes simply that an executive search is under way that could be a catalyst for growth at a time when the stock is trading near recent lows.

CAPS player orcboy6699 may have nailed the reason for a new CEO earlier this year, when he pointed out the alienation the company suffered as a result of management's actions:

Spent the last 3 years getting their act together. Spent tons of money getting to this point. Those efforts/investments, particularly in their new BIOX plant, are just about ready to pay off. Additionally, they had the bad habit of overpromising and underdelivering. They alienated a lot of investors, institutional and retail, in doing so, I'd like to think they've learned their lesson in that regard and, if/when that's proven to be the case, a lot of money will jump back in. Of course, this is a gold mining company. You're gambling on them finding more gold and gambling on the price of gold. Investing in any company is a gamble. This is a bigger gamble ... but the potential for very large returns are certainly there.

He's right that gold-mining companies have been a notoriously bad gamble, but sometimes things come up aces. For instance, rival Newmont Mining (NYSE:NEM) has rewarded investors over the past six months with a 25% increase in its share price. Now, it could be Golden Star's turn.

A great opportunity for you
That's the current word on Golden Star, but what are your thoughts? Are these four-star stocks still investment-grade material? On Motley Fool CAPS, your input can ultimately influence how they're rated. Outperform or underperform, near-term or well in the future, your opinion counts.

Sign up today for Motley Fool CAPS. It's completely free. Let's us hear what you have to say about the great -- and almost great -- companies that interest you.

Sigma Designs is a recommendation of Motley Fool Rule Breakers. Get a 30-day free-trial checkup to see all of the market-beating recommendations.

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. Wal-Mart is a recommendation of Motley Fool Inside Value. Starbucks is a Stock Advisor selection. The Motley Fool has a disclosure policy.