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, they rank higher than most of the other 5,400 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 approaching greatness. Here are a handful.

  • American Eagle Outfitters (NYSE: AEO)
  • GMX Resources (Nasdaq: GMXR)
  • Great Basin Gold (AMEX: GBG)
  • Northern Oil & Gas (AMEX: NOG)
  • Zoltek (Nasdaq: ZOLT)

Some of these names might surprise you. For example, industry stars Aeropostale (NYSE: ARO) and Buckle outsold American Eagle Outfitters throughout much of the recession. But in November, American Eagle's same-store sales were flat while Aeropostale went negative. American Eagle is looking to expand to Japan, perhaps taking a page from Coach's playbook, which has found great success there. Almost great? Even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold.

And Northern Oil & Gas has proven to be even more formidable as a land acquisition company than as a driller, making it one of the top long-term picks of a Foolish expert in resources. Shares are up 130% this year. Because the 170,000-plus CAPS members have chosen these companies as less obvious sources for tomorrow's great buys, let's see why they might merit your attention.

In the sight of greatness?
Because of its exposure to natural gas, GMX Resources hasn't been as fortunate as Northern Oil & Gas, and it has fallen 60% in 2010. While it has tried to protect itself from depressed natural gas prices by having an active rolling hedge program, GMX Resources has been forced to plan for capital spending cuts next year while hoping it can drill more wells with fewer rigs.

Despite the tough market, CAPS member Charlie1368 is optimistic about the company.

GMX Resources has amassed a body of assets that give it a solid competitive moat for at least the next few years. Trading at a discount to these assets which can produce long-term earnings potential, GMX Resources is a great value. Add in a decent balance sheet, solid cash flow, lots of insider buying, and bullish options sentiment, and you have a great buy.

More than 95% of the CAPS members rating the company expect it to outperform the broad market averages. Tell us what you think on the GMX Resources CAPS page.

Dirt cheap?
With gold at record prices, the promise of Great Basin Gold to move from a development company to a producer at its Hollister mine in Nevada and the Burnstone project in South Africa have helped propel its shares.

These are supposed to be low-cost projects, but the company's recent earnings report showed rising expenses caused by a large pre-tax loss. Great Basin Gold will need to get its mines producing to help offset that, and while investors seem excited by Hollister, the federal Mine Safety & Health Administration put it on a safety-watch list, which could be a setback. If nothing else, it brings to mind coal miner Massey Energy (NYSE: MEE) as regulators assess its commitment to safety, which led to the resignation of its CEO.

CAPS All-Star 100ozRound prefers to look at Great Basin as a gold producer.

Great Basin Gold is about to go from a development company to a full on producer. The company expects the Hollister mine to average around 110,000 [ounces] GEO annually (when complete) and Burnstone should reach an average of 250,000 oz per year. They expect to start sending their first gold from the Burnstone mine by the end of this month (October 2010)

Not sure if Great Basin is the right for your portfolio yet? Add the stock to your watchlist to get all the Foolish news and analysis gathered for you.

A big opportunity
Shares of carbon fiber manufacturer Zoltek went vertical this month after a poor earnings report at the end of November had sent the stock tumbling. Beholden as Zoltek is to turbine maker Vestas, which accounts for roughly half of its revenues, the news that Vestas was closing plants was bound to have an impact.

Insiders, though, apparently agreed with the Fool's Anders Bylund to accept the volatility in Zoltek's stock and buy on the dips. At least three directors have bought a total of at least a half-million dollars worth of stock in December, showing confidence that Zoltek will achieve consistent profitability.

Because 95% of CAPS members rating Zoltek also seem to agree, why not give it a spin on the Zoltek CAPS page and add the stock to the Fool's free portfolio tracker?

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.

Coach is a Motley Fool Stock Advisor pick. The Fool owns shares of Aeropostale and Coach. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. 

Fool contributor Rich Duprey owns shares of Aeropostale but does not have a financial position in any of the other stocks mentioned in this article. You can see his portfolio. The Motley Fool has a disclosure policy.