Some companies are obviously great investments -- in hindsight. Sure, we should have bought Starbucks at its IPO and earned hundredfold 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' rating system, they rank higher than most of the other 5,300 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 companies approaching greatness:

  • Cal-Maine Foods (Nasdaq: CALM)
  • Walter Industries (NYSE: WLT)
  • Western Digital (NYSE: WDC)
  • Jinpan International (NYSE: JST)
  • General Moly (AMEX: GMO)

Some of these names might surprise you. Western Digital, for example, has been making hard drives for computers for what seems like forever. Almost great? Even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold. However, some of the 83,000 CAPS investors chose these companies as less obvious sources for tomorrow's great buys, so let's see why they might merit your attention.

A coal-black heart
After spinning off its Mueller Water (NYSE: MWA-B) division last year, Walter Industries was essentially a coal-mining company at heart, but one that also produced natural gas and built homes, to boot. Considering the state of the housing industry these days, it's really a wonder that the Jim Walter Homes division of Walter isn't in worse condition than it is. So what's really driving the pumps these days is coal, and expected metallurgical coal contracts in excess of $100 a ton should bode well for Walter.

Its mining operations are in Alabama's Black Warrior River basin, the largest coal mining area in the Deep South and the seventh-largest in the country. Alabama itself is the 14th-largest coal-producing state, producing more than 20 million tons annually valued at more than $1 billion.

About 64% of Walter Industries' revenue comes from these operations, and the company is anticipating much of the growth it expects this year in the second half as it adds a lower-cost "longwall" unit to one of its mines. Yet even with higher coal prices, Walter Industries might face headwinds because of housing. It has taken to closing 36 sales centers and cutting the segment's workforce by 25% for 2008. Yet by sticking to its knitting of building homes and not being a land developer, when housing turns -- and it will, eventually -- Walter ought to be well-positioned.

CAPS investor kmorley123 likes Walter's more streamlined operations and wrote just a couple of weeks ago that Wall Street has ignored the stock because of its many moving parts. With a more singular focus, kmorley says, Walter should outperform the market:

Walter is a company that was poorly valued by the market for many years largely because analysts and investor's didn't understand how to value the conglomerate. It didn't help that Walter was barely profitable a few years back. With Walter's simpler structure following the Mueller spinoff, company's value becomes more obvious.

That's what alamobull, another CAPS player, feels will help Walter unlock the value in its remaining business:

[S]ecular growth stock at outstanding value with coal properties for export of metallurgical coal, also have [natural] gas assets ... selling off financial and housing subsidiary to generate cash for dividend or reinvestment.

Of course, not all CAPS investors are buying coal in Newcastle. All-Star tenmiles feels that the heavy debt load Walter carries merely prices it fairly at current levels, while the future is dicier.

A great opportunity for you
You've heard the latest on Walter Industries, but do you agree? Are these four-star stocks still investment-grade material? On Motley Fool CAPS, you can give your input, which could ultimately influence how these stocks are rated. Outperform or underperform, near-term or well in the future, your opinion counts.

Signing up for Motley Fool CAPS is free. Let's hear what you have to say about the great and almost-great companies that interest you.

Walter Industries and Mueller Water are recommendations of Motley Fool Hidden Gems. You can get a 30-day free trial of any of the Fool's newsletter services.

Fool contributor Rich Duprey owns shares of both Walter Industries and Mueller Water, 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.