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 recent four-star firms approaching greatness. 

  • Allos Therapeutics (Nasdaq: ALTH)
  • Conexant Systems (Nasdaq: CNXT)
  • Level 3 Communications (Nasdaq: LVLT)
  • Melco Crown Entertainment (Nasdaq: MPEL)
  • RF Micro Devices (Nasdaq: RFMD)

Some of these names might surprise you. For example, Level 3 Communications is successfully increasing competitive pressure on Akamai (Nasdaq: AKAM), glomming onto Akamai customer Hulu to deliver content over the Internet. Almost great? Even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold.

Fabless semiconductor maker Conexant Systems is another company that has had the last laugh on Wall Street, and as the new management team continues to adjust to the sector's competition, the market should appreciate its leaner look.

Let's dig a little deeper into why these stocks might merit your attention.

In the sight of greatness?
The wider annual loss that Allos Therapeutics reported last month shouldn't cause concern among investors, since it shows management's commitment to support its injectable drug Folotyn. Used to treat relapsed or refractory peripheral T-cell lymphoma, Folotyn promises to be a transformative drug for Allos since it is the only FDA-approved drug for this indication.

Following the FDA's accelerated approval last September, Folotyn has already generated over $4 million in sell-through sales for Allos, sales its distributors have made to health-care providers. The wider loss came as a result of increased marketing costs for the drug.

Ninety-five percent of the CAPS members rating Allos believe it will outperform the broad market averages. You can tell us on the Allos Therapeutics CAPS page whether the biopharma will transform itself further still.

On the shoulders of giants
The casino industry has been coming up aces these days. It's laughing at critics (including me) who thought the decision by Las Vegas Sands (NYSE: LVS) and MGM Mirage to take on debt to open lavish new facilities in Macau at a time when the industry was awash in capacity was foolhardy at best. Instead, shares of both casino operators have soared over the past year, rising 253% and 174%, respectively.

Yet the risks remain if you look at Melco Crown Entertainment, a Macau gambling industry pure play, whose stock has been one of the worst performers in the industry, remaining essentially flat over the past 12 months. It will release earnings tomorrow and analysts are anticipating a loss, albeit narrower than a year ago, despite revenue that is expected to rise more than 150%.

CAPS member luke77 isn't concerned, saying the long-term trend is for growth:

Well positioned in Macau which is the growth story for the future in casinos. People will not stop gambling and as the world economies recover numbers will start looking better.

A big opportunity
Perhaps better known as a chip maker powering the rise of the mobile Internet, RF Micro Devices recently said it successfully made the first photovoltaic cell using high-volume gallium arsenide (GaAs) machinery, the result of an agreement with the Energy Department's National Renewable Energy Laboratory to research ways to produce high-performance multijunction solar cells in commercially viable volumes. RF Micro hopes to begin production in significant quantities by 2012.

With its expertise in the GaAs market, RF Micro Devices is seen as a stable choice by investors like CAPS member Justajock33:

Just a solid company. Great ideas, great niche. Bought at $4, still reccomend now at $5 and will continue north of $7 per share. at this price, anyone can afford to buy 100 shares, sock them away and watch it grow!

A great opportunity for you
Investor sentiment suggests these four-star investments might 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.

Akamai Technologies is a Motley Fool Rule Breakers pick. Melco Crown Entertainment is a Motley Fool Global Gains selection. Try any of our Foolish newsletter services today, free for 30 days.

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 has a gold-plated disclosure policy.