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 5,000+ 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 them.

  • Hasbro (NYSE:HAS)
  • Illumina (NASDAQ:ILMN)
  • Southwestern Energy (NYSE:SWN)
  • Wal-Mart Stores (NYSE:WMT)
  • WuXi PharmaTech (NYSE:WX)

Some of these names might surprise you. Toymaker Hasbro has been entertaining families with games for years. Almost great? Even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold. However, the 125,000-plus CAPS members chose these companies as less obvious sources for tomorrow's great buys, so let's see why they might merit your attention.

In the sight of greatness
Despite December sales numbers that underwhelmed analysts, Wal-Mart looks to be one of the only retail operations that has a chance of making a go of it in this economic climate. Part of the expectations for Wal-Mart to produce better numbers resided in the belief that it would spur greater sales across all product categories. In reality, however, analysts found amid the rubble of retail that consumers were buying mainly necessities. Companies like supermarket chain Kroger (NYSE:KR) that also offer a decent value proposition on the basics have also been doing well.

As the economy has shown no signs of strengthening anytime soon, however, it seems apparent that Wal-Mart has a good chance to show some sales growth here. The deep discount retailer still has its detractors, of course, despite the obvious benefits it confers to families trying to stretch their dollars, but CAPS member Cellarhold says there's no other retailer he'd buy:

The only retailer I would want to own here. They will continue to pick up more customers as consumers become even more price conscious. The stock is on sale for $47 and appears to be a pretty good entry point.

R&D'ing M&A
(NYSE:PFE) bid for Wyeth shows that consolidation is rolling through the pharmaceutical industry, and with biotech shares at depressed prices, they'll continue to be attractive targets. Yet the trend toward outsourcing R&D to China is also likely to move ahead, and contract research organization (CRO) specialist WuXi PharmaTech could become a monster stock as a result.

Top-rated CAPS All-Star member TMFBreakerThiel finds the contract research angle for WuXi to be the most interesting aspect of the company. And considering its price, it might be worth the gamble:

I like the CRO business (contract research...not drug development, as some seem to think) as a secular trend, and WuXi is the lower-cost Chinese solution. Perhaps not the greatest business moat, but at this price, I'll take the risk.

All-Star member OklaBoston finds Illumina, a manufacturer of DNA sequence analysis equipment, to be a likely candidate to outperform the market:

This stock got added to the NASDAQ 100 index on Dec. 15, 2008. That will get the attention of mutual fund managers, I think. Also, if I correctly interpret what I see on other websites, management has got it's head on straight as far as placing more emphasis on the Co.'s long-term financial health than on near-term profitability. Motley Fool members should approve of that, shouldn't they?

A great opportunity for you
These four-star investments seem to be on their way to five-star greatness, and 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's hear what you have to say about the great -- and almost-great -- companies that interest you.

Pfizer is a Motley Fool Income Investor selection. Wal-Mart and Pfizer are Inside Value recommendations. Illumina and Hasbro are Stock Advisor picks. The Fool owns shares of Pfizer. Try any of our Foolish newsletters today, free for 30 days.

Fool contributor Rich Duprey owns shares of Wal-Mart and Kroger but does not have a financial position in any of the other stocks mentioned in this article. You can see his holdings here. The Motley Fool has a disclosure policy.