Some companies are obviously great investments -- in hindsight. Sure, we should have bought Starbucks at its IPO and earned huge 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 5,500 stocks in the CAPS universe, but they're just shy of superstardom. Their five-star peers get all of the attention, but we can still sift through CAPS to find four-star companies approaching greatness:

  • Ivanhoe Energy (NASDAQ:IVAN)
  • ImClone Systems (NASDAQ:IMCL)
  • GenVec (NASDAQ:GNVC)
  • National Coal (NASDAQ:NCOC)
  • Cree (NASDAQ:CREE)

Some of these names might surprise you. Biotech company ImClone Systems, for example, has been helping cancer patients with its Erbitux treatment for a while now. 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 110,000-plus CAPS investors chose these companies as less obvious sources for tomorrow's great buys, so let's see why they might merit your attention.

In the thick of it
With fuel prices so high, there's been a lot of discussion recently about the economics of extracting oil from tar sands. Ivanhoe Energy may enjoy another boost if an SEC proposal gets approved allowing oil sands to be included in the tallies of reserves. Right now, they can't be figured in. Being able to count them into the mix would boost reserve numbers and possibly valuations.

Some CAPS participants figure that Ivanhoe's restructuring will help it prosper. As player unvrsldeflation wrote in a pitch from March: "This company is a major player in heavy oil upgrading that is restructuring itself to take advantage of its expertise. They will be big in Canadian oil sands as well as conventional heavy oil, what the world mostly has left, in various places around the world."

Another cancer therapy
Like ImClone, GenVac is working on therapies to treat various forms of cancer, with its lead TNFerade treatment. It recently reported encouraging phase 1 clinical test results on head and neck cancer with TNFerade in combination with chemoradiation.

CAPS investor bmconnor finds TNFerade a worthy therapy for further testing and sees the prospects as promising:

GenVec is nearing an interim assessment by the FDA on the efficacy of their main product TNFerade on Pancreatic cancer. According to their latest presentations the efficacy of this drug on esophageal cancer looks extremely promising. The median for survival in patients has been lifted from a 9 - 18 month median range to a 48.6 month median! You can read the latest presentation on their website, but this is very exciting news for those of us in this stock for the long haul and for anyone that has a loved one with cancer.

Belle of the ball?
These days, Cree has to be feeling a little like Cinderella: She's been left behind to do the dirty work while everyone else is off at the ball. Color Kinetics was bought by Royal Philips Electronics (NYSE:PHG), Osram is in a joint venture with Siemens (NYSE:SI), and GE purchased GELcore. Yet with the mandate to phase out incandescent bulbs now a reality, Cree is sitting pretty in the solid-state lighting industry and could end up outshining all of the others now dancing at the party.

It's the LED potential for supplanting even compact fluorescents that has many investors lighting up with the possibilities. PuzzleMarketing says this is a "small cap industry leader with [huge] market potential especially with [imposed] government regulations for the elimination of incandescent bulbs."

Others still hold out hope for a buyout somewhere down the road. As ltgrowth123 puts it:

LED technology will eventually hit domestic households as primary source. thinning profit margin is a concern. possible buyout target years down the road.

A great opportunity for you
You've heard directly from the CAPS community on some of these stocks approaching greatness, but do you agree? Are these four-star candidates 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.