For every stock out there screaming "buy me," others simply give us a nudge and a nod. While all the attention might be focused on their five-star peers, we can sift through Motley Fool CAPS to find four-star stocks giving us the "high sign" they're approaching greatness. 

These opportunities -- including familiar names and beaten-down companies -- rank higher than most of the other 5,400 starred companies, and it pays to investigate their potential. For consideration today I've got these three stocks on their way to fame.

  • Boeing (NYSE: BA)
  • Hansen Medical (Nasdaq: HNSN)
  • Rentech (AMEX: RTK)

As the 170,000-plus CAPS members have chosen these companies as less obvious sources for tomorrow's great buys, let's see why they might merit your attention.

In the sight of greatness?
As much as the endless delays associated with Boeing's Dreamliner 787 represent a real threat to its business, sooner or later Boeing will actually begin delivering the jumbo planes. But a court case that until now has been flying pretty much below the radar also poses a threat.

The National Labor Relations Board (NLRB) is going after Boeing for actions it took after complaining about the machinists union at its Washington facility going on strike four times in 10 years and costing it billions of dollars in lost business. It opted to open a second manufacturing plant in right-to-work South Carolina and has hired 1,000 workers. The NLRB says the decision to open the second, nonunion facility was illegal because Boeing was being punitive. Yet Boeing notes that the new plant affected not a single union job in its Puget Sound facility, and it's actually expanded the workforce there by 2,000 employees.

But let's also understand that South Carolina provided Boeing with $900 million in tax incentives. States have often used taxpayers' money to lure companies. Over the years, taxpayers have footed the bill for wealthy companies like Dell (Nasdaq: DELL), Google (NYSE: GOOG), and Intel operations, while my home state of New Jersey is joined at the hip to the pharmaceutical industry.

Because these arrangements are so dicey, though, states began enacting clawback provisions: If the business didn't come through on its promises, it had to refund a portion of the handout. Dell had to repay North Carolina millions when the recession crushed job hopes there. South Carolina and Boeing may end up regretting the decision to go on the government dole.

CAPS member Larshans thinks Boeing has plenty of business opportunities to rise above any squabbles:

The 787 will start deliveries someday, hopefully soon. Tanker deal is in the books. About 340 billion order backlog. The defense spending for [Boeing] products probably won't decline much.

Take a flier on the Boeing CAPS page and let us know if the plane maker's new facility will ever gain altitude.

Paging Dr. Robot
As Intuitive Surgical (Nasdaq: ISRG) and Accuray have proven, surgical robotics is a lucrative business. Many medical device makers look to break into the field, hoping to achieve similar success. MAKO Surgical (Nasdaq: MAKO) is looking to score victory in minimally invasive knee surgery, while Hansen Medical's Sensei-X robotic catheter system seeks to revolutionize cardiovascular surgery.

Yet the process is difficult, and both MAKO and Hansen have thus far proved more adept at burning through cash than at turning the surgical world on its head. But CAPS member Calinvestments points to the role Hansen chairman Frederic Moll plays: "So the same guy who is responsible for [Intuitive Surgical] and MAKO is doing the same thing again with [Hansen]? Not that complicated, buy."

You can follow along by adding the stock to the Fool's free portfolio tracker and see if there's anything to make you to declare, "Danger, Will Robinson!"

Feeling gaseous
The Energy Department cut alternative fuels developer Rentech out of the financing loop this time around, and with its biomass gassifier plant hanging in the balance on receipt of those funds, investors pummeled the stock on news of the rejection.

Yet Rentech has other projects it's moving forward on, so there's little danger of it going out of business anytime soon. Its Olympiad Renewable Energy Centre will start producing low-carbon jet fuel when it opens in 2015 and it just acquired a majority stake in ClearFuels Technology, an advanced biofuel technology company.

CAPS member TravisRcroteau notes the regularly scheduled projects that will go live over the next few years as reason to see Rentech as a viable investment:

They have an attractive outlook with phased projects coming online in the next couple years. I believe this is a great opportunity to score an emerging stock at an unbelievable price.

You can gas up on the Rentech CAPS page and add it to your watchlist to keep track of all the news and analysis about this alt fuels play.

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