Some companies are obviously great investments -- in hindsight. Sure, we should have bought Starbucks at its IPO and earned hundreds of percent return 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 5,400 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 firms approaching greatness. Here are several to investigate:

  • Oracle (Nasdaq: ORCL)
  • Marvell Technology (Nasdaq: MRVL)
  • IMAX (Nasdaq: IMAX)
  • American Railcar Industries (Nasdaq: ARII)
  • Buffalo Wild Wings (Nasdaq: BWLD)

Some of these names might surprise you. Wide-screen movie maker IMAX, for example, has been wowing audiences with its sensory immersion technology for some time. Almost great? Even familiar names can offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold. But the 86,000 CAPS investors chose these companies as less obvious sources for tomorrow's great buys, so let's see why they might merit your attention.

Making tracks for profits
It's not only Warren Buffett who's buying railroad-related stocks. Carl Icahn is another billionaire investor who sees value in rails, and he's rolling to acquire and possibly consolidate the rolling stock industry. He controls more than half of the stock in American Railcar -- a manufacturer of covered hopper and tank railcars -- and used his position there to acquire a near 10% stake in Greenbrier Companies (NYSE: GBX), another railcar maker. He wants to explore combining the two operations.

A number of railcar companies have made themselves prime candidates for a merger. The industry is cyclical and while some in the business like American Railcar post growing profits, others like FreightCar America (Nasdaq: RAIL) have seen declining revenues and earnings. The latter might be positioning itself as a takeover candidate.

Certainly when Buffett acquired his 60% stake in Marmon Holdings recently, one of the pieces in the 125-piece jigsaw conglomerate that caught his eye was Union Tank Car, the oldest tankcar lessor and builder in the country. Undoubtedly it will make a complementary addition to his railroad holdings.

In this pitch from last November, CAPS player Phonodelic likes the fact that Icahn is a significant stakeholder in American Railcar and finds it more financially secure than many of its rivals.

Carl Icahn ... controls it now, therefore is unlikely to buy more back personally ... It has held up very well recently when the market tanks, and better than [Greenbrier], [Trinity Industries], and [FreightCar America] ... Building a new line which can build other car types, including coal cars and intermodal flats. Building inhouse component parts capacity (wheels, bolsters, couplers) to prevent supply shortages. All new manufacturing plants in right-to-work southern states.

CAPS All-Star Wollac, with a 99.40 player rating, found the company attractively priced last September after an earnings miss, and fully expected it to meet or beat analyst projections for the following two quarters.

This stock was battered substantially on one quarter's missed projections due to a slowing down of sales. However as oil prices continue to rise, shippers and truckers will continue to turn to rail as it is the cheapest way to haul goods when oil rises ... Although battered and at a 52 week low, I see this small stock reversing course when it meets earnings expectations next quarter, and beats expectations the following quarter.

Turns out, American Railcar missed expectations for the first quarter reported after this pitch, but handsomely beat forecasts last quarter.

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

IMAX is a recommendation of Rule Breakers. Buffalo Wild Wings is a Motley Fool Hidden Gems selection. You can get a 30-day free trial to any of the Fool's investment services. The Motley Fool owns shares of Buffalo Wild Wings.

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 disclosure policy.