Some companies are obviously great investments -- in hindsight. Sure, we should have bought Starbucks at its IPO and earned astounding returns 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 5,600 stocks 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:

  • Advance Auto Parts (NYSE: AAP)
  • Powerwave Technologies (Nasdaq: PWAV)
  • Edge Petroleum (Nasdaq: EPEX)
  • McDonald's (NYSE: MCD)
  • Kopin (Nasdaq: KOPN)

Some of these names might surprise you. Hamburger king McDonald's, for example, has been serving billions for years and even has its golden arches in Tiananmen Square. Almost great? But even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold. The 97,000 investors at CAPS chose these companies as less obvious sources for tomorrow's great buys, so let's see why they might merit your attention.

Riding the wave
If the CEO of Nokia (NYSE: NOK) is correct, even in the face of rising food and fuel prices, sales of cell phones should remain steady because they have become a necessity, even in emerging markets. Unfortunately, analysts and the markets don't agree. Despite posting revenue that was 28% higher than the year before and operating profits that rose 20%, shares of the Finnish handset maker were thrashed by 14% yesterday as investors focused on Nokia's cautious outlook for the rest of the year.

Whose vision ultimately proves more correct will impact how Powerwave is perceived, because it gets more than a third of its revenue from Nokia (via Nokia Siemens Networks). Another 16% comes from Alcatel-Lucent (NYSE: ALU), meaning more than half of its revenue is riding on the ability of these two companies to get more people to buy cell phones.

It's been a good relationship for Powerwave up 'til now, considering that Nokia has almost 40% of the global handset market -- more than the next three players combined, according to the market researchers at Strategy Analytics. Yet the big contracts haven't been able to help Powerwave shares recover from the drubbing they took two years ago, when it had a series of earnings misses. The stock collapsed from its lofty $16 level to its current level in the low single digits.

Investors may want to look a little more closely at Powerwave's valuation these days, as service providers have begun to spend more to upgrade their networks. CAPS investor NeroSagetrade sees the stock as appropriately valued for the first time since it went public. It might not be cheap enough to be a buyout candidate, but the industry looks ripe for consolidation. Here's an excerpt from NeroSagetrade's early March pitch:

Powerwave Technologies may be at a respectable valuation for the first time since it became listed over a decade ago. [Powerwave] is trading below both its book and sales valuation ... The thing that really stands out ... other than its erratic earnings reports, is the fact that [a large portion] of their business comes from Nokia, and Nokia has been performing more solidly than any of the other handset providers recently. As long as Nokia and Siemens continue to perform well I don't see much downside from here.

A great opportunity for you
You've heard directly from CAPS investors on Powerwave, 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 us hear what you have to say about the great -- and almost-great -- companies that interest you.

Powerwave is a small cap that could be bound for better times again. Check out Motley Fool Hidden Gems for other small caps on their way to greatness with a free 30-day trial.

Fool contributor Rich Duprey does not have a financial position in any of the stocks mentioned in this article. You can see his holdings here. The Motley Fool owns shares of Starbucks, which is an Inside Value and a Stock Advisor pick. The Fool has a disclosure policy.