Some companies are obviously great investments -- in hindsight. Sure, we should have bought Starbucks at its IPO and earned a hundreds of percent return over the years. 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 5,500 companies in the CAPS universe, 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:

  • Abaxis (Nasdaq: ABAX)
  • Anadigics (Nasdaq: ANAD)
  • CF Industries (NYSE: CF)
  • Linn Energy (Nasdaq: LINE)
  • Schering-Plough (NYSE: SGP)

Some of these names might surprise you. Pharmaceutical giant Schering, for example, has been developing drugs for years; its recent setback along with Merck (NYSE: MRK) over Vytorin has been a black eye for the company. Almost great? Even familiar names -- particular ones with long pipelines -- can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold. However, the more than 95,000 CAPS investors chose these companies as less obvious sources for tomorrow's great buys, so let's see why they might merit your attention.

Building a better model
Sounding like a specialty craft from the guild era of the Renaissance, master limited partnerships are indeed a special breed of incorporation. MLPs are considered "pass-through" entities, meaning they don't pay taxes on the partnership's earnings; instead, earnings are passed through to the partners and taxed on an individual basis. Generally, only certain types of businesses are allowed to be organized this way, such as those deriving 90% or more of income from interest, dividends, real estate, commodities, minerals, or other natural resources like timber.

That brief background is necessary to understand why oil and gas acquisition and development company Linn Energy is attracting investor support. It is structured as an LLC, or limited liability company, in a manner similar to an MLP, but management and shareholders have equal standing when it comes to distributions. It has been adding to its portfolio of properties with strategic acquisitions, including a number in the important Marcellus and Woodford Shale areas, which gives it some great potential development opportunities.

With sharply narrowing losses and revenues ahead of expectations, the oil and gas play is becoming more attractive. It was that sort of expectation of growth that had CAPS investor Stasi lay out a comprehensive thesis for Linn Energy in December. Here's an excerpt:

[A] gas-weighted LLC-structure oil & gas producer. Since their IPO in early 2006 they have been very acquisitive & their original asset base in Appalachia now represents less than 15% of total reserves. Since these acquisitions were funded primarily via PIPEs, there is a large overhang of unregistered units that are just starting to come to market. As large acquisitions start to drive distribution growth, sales of newly registered PIPE shares are depressing unit price, leading to a great opportunity to purchase tax-advantaged cash flows.

That top-rated bull pitch for the oil and gas company probably sums up the sentiments of the 93% of CAPS investors who also see Linn Energy outperforming the market. Another CAPS player, Harry0925, sees the company's shale assets as a "free call option on NG" in this very recent pitch:

Should return 50-65% plus over the next one to two years as MLPs come back into favor. There is a PIPE overhang that is wearing off in this stock. Proven reserves are worth about 4.7B, probable reserves and large interests in Marcelus and Woodford Shale acreage are free... A [dividend discount model] yields price of about $30 ... and shale assets are free call option on NG.

A great opportunity for you
You've heard directly from CAPS investors on Linn Energy, but do you agree? 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 in Merck, but does not have a financial position in any of the other stocks mentioned in this article. You can see his holdings here. Starbucks is a Motley Fool Inside Value and Stock Advisor selection. The Motley Fool has a disclosure policy.