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 four-star firms approaching greatness. Here are a handful of four-star firms approaching greatness.

  • BP Prudhoe Bay Royalty Trust (NYSE: BPT)
  • Lexicon Pharmaceuticals (Nasdaq: LXRX)
  • PDL BioPharma (Nasdaq: PDLI)
  • Prospect Capital (Nasdaq: PSEC)
  • Transatlantic Petroleum (NYSE: TAT)

Some of these names might surprise you. For example, BP Prudhoe Bay Royalty Trust was set up by BP in 1989 and owns a 16.4% stake of the first 90,000 barrels per day coming out the oil giant's Prudhoe Bay field in Alaska. With corporate profits shielded from taxes, it pays out a dividend currently yielding 9%. Almost great? Even unfamiliar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold.

And vertically integrated oil and gas producer Transatlantic Petroleum finally began selling gas out of its Turkish Edirne field in the Thrace Basin in April. With promising developments still on the horizon, it's easy to see why almost all the CAPS members rating Transatlantic have suggested it will outperform the broad market averages.

However, the 165,000-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?
Can Lexicon Pharmaceuticals overcome its history of shareholder dilution to make the stock a worthwhile addition to an investor's portfolio? The biotech has some promising drug candidates for treating irritable bowel syndrome, carcinoid syndrome, and diabetes, and it was good Phase 2 data received in January for the latter that had Lexicon raising cash in the equity markets again. It had a secondary offering earlier this year which effectively doubled the shares outstanding.

While current shareholder might suffer from the issuance of more stock as the share price has traded in a fairly narrow band, that's what it needs to do to fund its R&D needs. Meanwhile, Lexicon might look attractive a to a big pharma. Eli Lilly (NYSE: LLY), which has an 80-year history of treating the disease, might find its developments interesting.

More than 93% of the 281 CAPS members rating the tiny pharma believe it will turn in market-beating results. You won't dilute the opinions of others on the Lexicon Pharmaceuticals CAPS page by issuing your view there.

On the shoulders of giants
Legal disputes are nothing new in the biotech world, but PDL BioPharma sure seems to be having a spate of issues around its intellectual property. Most recently it was partner Roche saying the technology it's using to make Avastin and other drugs -- and paying royalties to PDL for -- isn't actually the technology described in the patents PDL holds. Now Roche never said it was going to contest the issue, but that's apparently what investors thought it would ultimately do as they sent PDL's shares plummeting.

But before Roche there was the snit it got into with AstraZeneca subsidiary MedImmune over PDL's Synagis, a respiratory treatment. It charged the pharmaceutical with breach of the license agreement, and stopped receiving revenue for the sales of the drug in December 2009. That contributed to PDL's revenue drop last quarter.

CAPS member calbarclay thinks PDL will suffer as a result of its legal problems, but 95% of members rating it think it overcomes the troubles. Tell us in the comments section below or on the PDL BioPharma CAPS page whether this is a patently good time to get in.

A big opportunity
Like Lexicon, Prospect Capital also frequently visits the equity market, though to grow and buy into businesses it needs to offer more shares too. But the decision to slash its dividend 26% might leave more of a sour taste in the mouths of investors than seeing their holdings diluted. The business development company, which earlier this year backed out of an attempt to woo Allied Capital away from Ares Capital (Nasdaq: ARCC), switched from a quarter distribution o $0.41 a share to a monthly distribution of $0.10, which lowered the annual payout to $1.20 from $1.64 a share.

That hasn't stopped CAPS member vinney11 from thinking the brainiacs running the BDC will still be able to find sufficient place to deploy their cash.

Recently cut dividend and changed to monthly versus quarterly distributions. Lots of Harvard types running this operation and they think there's a lot of good deals to put the cash towards. Still pays 12%. 

A great opportunity for you
Investor sentiment suggests these four-star investments still seem to 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's us hear what you have to say about the great and almost great companies that interest you.

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.