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 5,400 starred 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 firms approaching greatness. Here are a handful of four-star firms approaching greatness:

  • CenturyLink (NYSE: CTL)
  • Jamba (Nasdaq: JMBA)
  • North Star Realty Finance (NYSE: NRF)
  • SandRidge Energy (NYSE: SD)
  • Skyworks Solutions (Nasdaq: SWKS)

Some of these names might surprise you. For example, SandRidge Energy might be a smaller natural gas play than either Chesapeake Energy or Linn Energy (Nasdaq: LINE), but its just completed $1.6 billion acquisition of Arena Resources gives it a growing presence in the oil fields. Almost great? Even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold.

And rural telecom carriers CenturyLink and Windstream are suddenly on investors' radar, after Frontier Communications (NYSE: FTR) got hold of Verizon's rural assets. However, the 165,000-plus CAPS members chose 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?
When your product is so popular that even the burger joints want to get in on the action, you know you've got something special. Fruit smoothies were around long before Jamba burst on the scene, but their popularity, and the ubiquity of Jamba storefronts, has caught even McDonald's attention. The Golden Arches is introducing its own line of smoothies under the McCafe name. Jamba's success was also apparently enough for Yum! Brands, the parent of such fast-food palaces as KFC, Pizza Hut and Taco Bell, to get into the act, too.

With over 700 locations nationwide either company-owned or franchised, Jamba has plenty of room to grow to tap into the younger market that CAPS member Pilotguy05 considers the core of its future:

The health trend should continue as time goes on. They're captive audience is in the mid 20's and as that age group becomes older and has an increasing amount of disposable income, restaurants like this will become even more attractive.

On the shoulders of giants
With the commercial real estate sector barely hanging on, it's hard to imagine that real estate investment trust North Star Realty Finance is about ready to pop. Net lease arrangements, the one aspect of CRE mortgages that has done relatively well lately, really has helped the company hang on. In fact, last quarter's earnings were much worse than expected. Although North Star sports a juicy dividend yielding almost 14%, how sustainable is that payout?

The Wall Street Journal reports that "extend and pretend" in the CRE market is becoming a way of life for bankers trying to forestall writing down bad debts. By restructuring loans to give debtors new life, all the while hoping the market recovers, they'll only make the situation worse when it finally does implode down the road.

Despite North Star's poor performance recently, CAPS member NStefonich thinks that based on its financial situation it should be able to outperform:

From a valuation standpoint, this stock is cheap. Based on the last quaterly financials, compared to book value, this stock is a steal. Given a few years, stock should rise back up to $15 range.

A big opportunity
The push toward the mobile Internet has also generated strong free cash flows for Skyworks Solutions, which saw operating income more than double in the second quarter. It doesn't hurt in the least that Skyworks' technology has found its way into the iPhone 4. Apple reported that it sold 8.4 million units last quarter; according to Apple COO Tim Cook, the company's selling every iPhone it can make.

That's enough for CAPS member GearCat, who says that Skyworks has a history of beating earnings expectations:

A supplier of components for the iphone which has been sold out everywhere! Also, shows positive growth in EPS for the last three quarters.

A great opportunity for you
Investor sentiment suggests these four-star investments still seem to be on their way to five-star greatness. Still, 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.