Have you ever owned a tweener?

A tweener, dear Fool, is like your pal Chuck. Still a great athlete, Chuck no longer rules the hardwood with his 40-inch vertical leap. He's become what we sports addicts call a gamer. He passes more. He's developed a nice shot from the corner. And though he doesn't dunk as much, or as spectacularly, the way he once did, Chuck is still a force in the paint.

What we fans don't know is how long Chuck will be in the starting lineup. Chiseled veteran Abe has a wicked hook shot that won't quit. And Larry, the little guard whose hip-shaking moves smoke the defenders, has the makings of a future superstar. Both are vying to cut into Chuck's minutes on the floor.

In Foolish parlance: Chuck is a tweener, Abe is a Rule Maker, and Larry is a Rule Breaker.

Growing up is hard to do
The stock market has plenty of Chucks. They'll either create billion-dollar fortunes as they come to dominate industries, as Cisco, Microsoft (NASDAQ:MSFT), and Google have, or they'll be destroyed in the process, as Gateway was.

Therein lies the problem. Investing in tweeners can be dangerous and  exceptionally profitable. The trick is in picking your winners well, as David Gardner has. He produced nine years of 20% average returns hunting for misunderstood multibaggers in the making. His team at Motley Fool Rule Breakers continues the tradition today.

Let's have the list
You, too, can join in the effort, thanks to Motley Fool CAPS. Each week, we'll use the database to find three-star stocks (out of a possible five) that are expected to boost earnings by at least 15% annually over the next five years. Here is today's list.

Company

CAPS Rating

5-Year Growth Estimate

eHealth (NASDAQ:EHTH)

***

31.7%

Illumina (NASDAQ:ILMN)

***

28.7%

Corporate Executive Board (NASDAQ:EXBD)  *** 18.5% 

EPIQ Systems (NASDAQ:EPIQ)

***

17.5%

Finisar (NASDAQ:FNSR)

***

17.5%

Sources: Motley Fool CAPS, Yahoo! Finance.

Bear in mind that this isn't a list of recommendations. Instead, I offer these stocks as candidates for further research. But of this group, it's digital insurance agent eHealth that interests me most.

Why? Math, really. Roughly 47 million Americans are without health insurance, and millions more may be forced to purchase their own as retirement age approaches. eHealth caters to this group with 5,000 insurance products that it offers through its websites -- ehealth.com and ehealthinsurance.com.

And business has been good. Revenue growth has accelerated in each of the past four years. Return on capital, meanwhile, is up from negative 4.9% in 2005 to positive 13.2% over the trailing 12 months. Talk about momentum.

Intrigued? Do your own due diligence, and then check in with thousands of other investors at CAPS. And, if you'd like, add your own commentary. You'll be helping your fellow Fools and testing your ideas at the same time. Click here to get started now; the service is 100% free.

See you back here next week for five more growth stocks stuck in the middle.

How great is growth? More than 10 stocks in the market-beating Rule Breakers portfolio have at least doubled. Discover their identities with a 30-day guest pass to the service. There's no obligation to subscribe.

Microsoft is an Inside Value pick. Corporate Executive Board is a Stock Advisor selection.

Fool contributor Tim Beyers, who is ranked 6,754 out of more than 65,000 participants in CAPS, is a regular contributor to Fool.com and Rule Breakers. Tim didn't own shares in any of the companies mentioned in this article at the time of publication. Click here for Tim's portfolio and here for his latest blog commentary. The Motley Fool's disclosure policy would prefer a little less conversation and a little more action.