You don't need the investing acumen of Warren Buffett or the riches of a trust fund baby to achieve financial success.

Small sums of money invested monthly in undervalued small-cap stocks offer hope for your greatest returns. They offer the best opportunities for growth because they're mostly ignored by the big investors.

Below, we screen for stocks under $3 billion in market cap, offering earnings surprises of 15% or more in the previous quarter, with long-term earnings growth forecast to be at least 15%. We'll then filter our findings through the collective investing wisdom of the 170,000 members in our Motley Fool CAPS community.

Here are some of the stocks this simple screen found:

Company

Market Cap

EPS Act. Vs. Est.

Avg. Analyst 5-Year EPS Est.

CAPS Rating (out of 5)

OpenTable (Nasdaq: OPEN) $2.7 billion $0.33 vs. $0.22 38% *
Power-One (Nasdaq: PWER) $801 million $0.49 vs. $0.40 21% ****
Zix (Nasdaq: ZIXI) $255 million $0.05 vs. $0.03 25% ***

Source: Yahoo! and Motley Fool CAPS.

Of course, this is not a list of stocks to buy -- just a starting point for more research. We need to look more closely at these companies to see whether analysts' faith in them is well-founded.

An alternative opportunity
Online reservation specialist OpenTable has doubled in value over the past six months and nearly tripled in the past year. The stock has been hitting new highs regularly and carries a valuation of near 200 on a trailing basis and almost 70 on forward estimates.

That kind of action is attracting short-sellers by the dozen. With some 23 million shares outstanding, more than 23% are sold short. It's either poised for a big fall or another huge run-up from a short squeeze. Critics maintain that it's getting harder to justify its lofty valuation, particularly as coupon distributor Groupon is getting closer to going public, and investors feel it may be a better way to get diners to the table.

Yet some analysts, even if they think the stock has gotten ahead of itself, still see OpenTable as a leader here that should be able to grow its share. Bank of America analysts, for example, say it ought to increase its share of seated diners from 9% to 60% even as the bank downgraded the stock to a hold.

CAPS members such as JoesCash overwhelmingly think OpenTable is going to underperform the market.

Way overvalued. The company has a decent idea and is making money, but 2.5b market cap? Nah.

And you'd be hard-pressed to convince the All-Stars of anything different since two-thirds of those rating the reservation specialist agree. But you can still get a seat at the table by giving us your views on the OpenTable CAPS page.

A bend in the road
The winds blowing against the alternative energy industry have hit gale force as American Superconductor's (Nasdaq: AMSC) largest customer, Sinovel, finally stopped placing orders for electrical components for its wind turbines. There's a lot of inventory Sinovel needs to work through before it can accept more.

Inverter makers Power-One and Satcon Technology (Nasdaq: SATC) had raised yellow flags earlier with weak earnings reports that suggested solar shops were signaling a slowdown, too. But with the possibility that gas could rise even more over the summer, the desire for alternative sources of energy will get a big boost.

Power-One also shows a huge short interest against its stock, with more than a third of shares outstanding sold short. Highly rated CAPS All-Star jmf1957 thinks such a sizable percentage indicates a problem.

Generally speaking, a short position of this percentage indicates something seriously wrong,information not privy to the general investing public,as of yet, or the 40% short side is going to be wrong, and caught in a short squeeze?

See whether Power-One will invert this high short stake into a squeeze by adding the stock to your watchlist.

Man the ramparts
CAPS member StiffArm111 suggests that a patent infringement lawsuit against email encryption specialist Zix will ruin its chances of attracting customers. Certainly, the plaintiff in the case, RPost Holdings, is brash enough that it brought suit against the Swiss postal service for patent infringement, apparently the first time anyone has sued an agency of a foreign government for violating a U.S. patent.

But being brazen doesn't confer righteousness. RPost suggests that anyone offering authentication of receipt of an email is in violation of its patents, and with the number of suits RPost has brought and won or settled -- including one against a service called Goodmail, whose clients included AOL (NYSE: AOL) and Yahoo! -- it seems they've got a strong leg to stand on.

You can register your own opinion on the Zix CAPS page and explain whether its business will be returned to sender.

Foolish final thoughts
Stock investing is not brain surgery. Finding good, undervalued companies is not as difficult as the professionals want you to think. You just have to commit to starting now, and do so regularly. Now's the time to begin!

OpenTable is a Motley Fool Rule Breakers pick. Yahoo! is a Motley Fool Global Gains choice. The Fool owns shares of Bank of America, Power-One, and Yahoo!. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. 

Fool contributor Rich Duprey does not have a financial interest in any of the stocks mentioned in this article. You can see his holdings here. The Motley Fool has a disclosure policy.