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 IPO and realized tens of thousands of percent returns over the years. Yet for every stock out there screaming "buy me," there are others that simply give us a nudge in the ribs and a knowing nod. 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 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 are just shy of achieving stardom. In the long shadows of stocks that garner 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, just as every stock is rated. The best and brightest of these players are considered All-Stars, and since they're correct more consistently than their peers, their opinions weigh more heavily in favor of (or against) a stock.

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:

  • Las Vegas Sands (NYSE:LVS)
  • MEMC Electronic Materials (NYSE:WFR)
  • Silicon Image (NASDAQ:SIMG)
  • Immersion (NASDAQ:IMMR)
  • CDC (NASDAQ:CHINA)

Some of the names you might find surprising. After all, anyone who has seen a picture of Las Vegas knows the Sands hotel and casino. 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 meaningful, 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.

Opportunity on a platter
It's these long term opportunities that can earn you the greatest profits. MEMC is the largest pure-play maker of silicon wafers and has benefited from making almost all of the key ingredient in wafer production -- polysilicon -- it uses. Semiconductor sales rose sharply in August, up 4.9% according to the Semiconductor Industry Association, and the industry is expected to outpace overall economic growth going forward. Trends for MEMC look favorable.

While chip sales remain key, it's the shortage of poly that has most CAPS investors seeing tremendous growth ahead. Top-rated All-Star tuffsledding points to it as significant, even if various industries experience a slowdown.

Continued shortage of polysillicon will result in sustained profit growth, regardless of the struggles of the solar power manufacturers. Already a double in my real portfolio, this one has a long way to go.

That's what another All-Star vkrish98 thinks, too, and points to its long-term contracts.

Two words "Polysilicon shortage"

The prices of this key ingredient in solar panels has skyrocketed. MEMC has a 10 yr contract with Suntech [Power] to deliver polysilicon. Countries like Spain are embracing solar energy and I see prices rising.

A great opportunity for you
That's the current word on MEMC Electronics, but what are your thoughts? Are these four-star stocks still investment grade material? On Motley Fool CAPS, you can give your input, which 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.

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. Suntech Power is a Rule Breakers newsletter recommendation. The Motley Fool has a disclosure policy. Microsoft and Wal-Mart are recommendations of Motley Fool Inside Value.