Ever since my original "5 Stocks Under $10" column seven years ago, I've been singling out attractive stocks that happen to be trading in the single digits.

Is it risky? You bet. Stocks don't trade for pocket change without a reason. Some are has-beens, struggling to convince the market that they can turn things around. Others are simply lurking in the shadows, well off of Wall Street's radars.

Few make it out of the penny stock muck, but that won't stop me from picking out the companies that I think have the catalysts to head higher. Let's go over this month's list.

Alvarion (Nasdaq: ALVR) -- $8.98
Is it too late to hop on the leading supplier of WiMAX equipment? The stock has risen 53% since being recommended to Rule Breakers subscribers two months ago, but I think the industry is still in its infancy. Whether it's the stateside consolidation or the bigger potential for WiMAX in emerging economies, Alvarion is at the right place at a fashionably early time.

The company posted respectable quarterly reports earlier this month. Revenue increased 29%, even though the company posted a small loss for the quarter. This is certainly a "feast or famine" scenario, but I like Alvarion's chances, given its growth, status, and cash-rich balance sheet.

Sirius Satellite Radio (Nasdaq: SIRI) -- $2.72
A lot of investors may wince at the mere mention of Sirius as an investment, but let's lay it all out on the table. The company continues to grow its subscriber base, quarterly losses are narrowing, and the pending merger with rival XM Satellite Radio (Nasdaq: XMSR) will result in billions of model-altering synergies.

This seems to be lost on Wall Street, which fears that the deal is still waiting for regulatory approval and that even Sirius has indicated that there are only so many concessions that it will be willing to make to get the deal done.

As a speculative play, I like Sirius. If the deal comes undone, the stock is already trading for less than it did when the merger was announced 15 months ago. In that time, Sirius has closed the subscriber gap with XM and has had plenty of time to drum up its Plan B strategy if the Federal Communications Commission shakes its head at the deal.

Builders FirstSource (Nasdaq: BLDR) -- $7.48
How bad have things gotten in the housing market? Well, let's just say that Warburg Pincus paid $23 a share for this industry supplier two years ago. Inside Value nibbled on it as a recommendation a year ago, when the stock had dropped into the teens. Today, investors can get in at a third of where it was two years ago.

Yes, it's bad. First-quarter revenue clocked in 34% lower. The company swung to a loss from a profit in a housing industry suffering through two years of deterioration. It wasn't going to be immune. However, Builders FirstSource has been gaining market share through the decline. Whether it's through weaker rivals buckling or savvy acquisitions, the company is positioning itself nicely for the eventual recovery. It may not happen for another year or two, but the upside will be substantial when it materializes.

Internet Brands (Nasdaq: INET) -- $6.48
These are acquisitive times in the dot-com world. With last week's $1.8 billion buyout of CNET Networks (Nasdaq: CNET), it may be a good time to warm up with online traffic magnets like Internet Brands.

Not all Web traffic is the same. If you're a search engine or an ad-driven media conglomerate, you want page views that can be easily monetized in lucrative areas. Internet Brands fits the bill with several sites devoted to automotive, travel, and real estate. Sure, running Loan.com may not seem all that attractive right now, but that will change in time. Until then, the company should do well with Autos.com, popular cruising travel website CruiseMates, and licensing the vBulletin message board platform.

Natuzzi (NYSE: NTZ) -- $3.77
Selling Italian leather furniture these days has to be like peddling hope to New York Yankees fans. The brand prestige is there -- for both the Yanks and Natuzzi -- but the losses continue.

On the stateside front, Natuzzi has the double whammy of trying to import suddenly pricier sofas where the housing market is mired in a slump. The United States used to gobble up nearly a third of the company's sales, so it's definitely a problem. Revenue is falling and the company is reporting losses instead of profits. It's hard to win when you're having problems pitching and hitting.

Thankfully, Natuzzi isn't as leveraged as other struggling furniture makers. You have to like the Global Gains stock pick's chances here, as it is trading at a fraction of book value, with a lot of that coming in the form of cold hard cash on the balance sheet.

Five for the road
Turnarounds never happen overnight. These five stocks aren't trading in the single digits by accident. If I'm right about the catalysts, though, they may not be trading in the single digits for too much longer.

Finding promising stocks while they're still cutting their baby teeth is at the heart of the Rule Breakers newsletter. You can check it out for free this month with a 30-day trial. There are more than a half-dozen active recommendations in the growth stock research service trading for less than $10 at the moment. Check those out, and I'll be back with more next month.