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.

  • Amylin Pharmaceuticals (Nasdaq: AMLN)
  • Atmel (Nasdaq: ATML)
  • Caterpillar (NYSE: CAT)
  • Ivanhoe Energy (Nasdaq: IVAN)
  • Skyworks Solutions (Nasdaq: SWKS)

Some of these names might surprise you. For example, Caterpillar is both a dominant player in the heavy machinery space, but its CAT logo is a well-known brand among those who have never driven a bulldozer. With its move to buy rival Bucyrus, it will become an even greater forceAlmost great? Even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold.

And oil exploration company Ivanhoe Energy moved past its chairman's shady past, quelling the skeptics who suggested it was a risky bet all on its own. As 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?
It was a bit of a surprise this past October when Amylin Pharmaceuticals got smacked down by the FDA, which decided that in addition to more information on the safety and efficacy of its Type II diabetes treatment Bydureon it also wanted Amylin and its partners Eli Lilly and Alkermes to submit the drug to a thorough QT test.

Amylin is trading well off its 52-week high, as the market holds an apparent dour view of its prospects. While the delay in approval is certainly disappointing, the biotech still has a portfolio of candidates that ought to help offset any faults found with Bydureon. Particularly in light of the failure of VIVUS and Arena Pharmaceuticals (Nasdaq: ARNA) to make it through the FDA gauntlet with their obesity treatments, Amylin has an opening for its own therapy, pramlintide acetate, which is expected to move into phase 3 testing next year.

More than 88% of the CAPS members rating Amylin also expect its pipeline to come through for it, rating the biotech to outperform the broad market averages. But you can tell us on the Amylin Pharmaceuticals CAPS page whether you agree it's got enough depth to break through.

Dirt cheap?
Tablet computers are changing computing, becoming one of the fastest-growing segments in the industry. Intel is starting up a division focused on tablets and mobile computers as those devices cut into PC shipments. When you include the iPad as a mobile computing device, it elevates Apple (Nasdaq: AAPL) to the largest mobile computer maker in North America and the third largest worldwide.

That helps explain why touch screen maker Atmel is on a tear. Its stock is up 150% this year, and its newest chipsets will power the next generation of touch devices including tablet, mobile computers, netbooks, and notebooks. Look for them in the latest development in computing, too: smartbooks, a class of mobile computers that combines features found in smartphones and netbooks.

For all that, highly rated CAPS All-Star Slappster still sees Atmel as an underappreciated and hidden leader:

Anyone see Q3 results?! They are eating Synaptics and Cypress alive in touch. In fact, they might be No. 1 right now. Nobody seems to talk about this one though. It's not the same company it has been.

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

A big opportunity
That push toward the mobile Internet is also working in favor of Skyworks Solutions, which saw operating income almost double in the fourth quarter. It doesn't hurt in the least that Skyworks' technology has found its way into the iPhone 4, especially since analysts are revising their estimates upwards that in 2011 Apple will sell as many as 60 million units.

Yet, even more than just Apple, CAPS member skivt says all phones will soon resemble the iPhone, and Skyworks will find its technology inside them:

Soon every phone will be a smartphone, and demand for SWKS's components will likely increase with the trend.

You can dial up the thought of other investors on the Skyworks Solutions CAPS page and 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 lets us hear what you have to say about the great and almost great companies that interest you.

Intel is a Motley Fool Inside Value choice. Apple is a Motley Fool Stock Advisor selection. The Fool owns shares of and has bought calls on Intel. Motley Fool Options has recommended buying calls on Intel. The Fool owns shares of Apple. 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 does not have a financial position in any of the stocks mentioned in this article. You can see his portfolio here. The Motley Fool has a disclosure policy.