One day in May, Jeffrey Montgomery emailed fellow Charleston software CEO Grier Allen and, "just for fun," made a bet.

Allen's company, Boomtown, was included in the annual Inc. 500 list of the nation's fastest-growing private companies in 2011 and seemed poised for a repeat listing in 2012. Montgomery's firm, O-matic Software, had also been spurting and had submitted its financials for consideration in this year's magazine.

So Montgomery bet Allen that O-matic would rank higher than Boomtown. The wager? A beer at a neighborhood bar conveniently located between Boomtown's office and Montgomery's house.Well, there was good news and bad news when the rankings were revealed. The good news was Boomtown, which sells to real estate brokers, and O-matic, which targets nonprofits, made the list.

The bad news, for Montgomery, was that O-matic's staggering 2,656 percent growth over the past three years somehow fell short of Boomtown's revenue increase over the same period, 3,085 percent.

"I owe him a beer at Moe's," Montgomery said Friday.

Although Inc. won't put the list online until today, subscribers got their magazines last week. The word soon spread that Boomtown had repeated at an even higher ranking (No. 96) than last year and that fellow Charleston Digital Corridor members O-matic (No. 118) and BiblioLabs (No. 338) had also made the high-profile business list, now in its 30th year.

"This validates basically where we are," corridor Director Ernest Andrade said, referring to the technology community in what some have called the Silicon Harbor.

Four other South Carolina companies were listed this year, led by Greenville-based Wireless Communications' 6,581 percent growth.

Charleston-based BiblioLabs, an on-demand and digital publisher, brought in $17.5 million in revenues last year, which was more than double Boomtown's and O-matic's revenues combined –- and it did it with only 15 employees. Its 1,111 percent three-year growth rate was just behind Facebook in the media category.

CEO Andrew Roskill attributed the growth to more channels and more content for its products, which increased by one this month when it released BiblioBoard, an iPad app featuring subject-specific primary source collections.

"The iPad-application business is the fastest growing piece of our business, for sure," Roskill said.

The company is now up to 25 employees and plans to move into new office space this fall.

Montgomery, who recently moved O-matic into new offices in North Charleston, attributed his company's growth to its flagship product, Import-o-matic, which acts like "a vacuum cleaner for bringing data" for Blackbaud Inc.'s fundraiser, the Raiser's Edge.

Allen said Boomtown's success is simply a result of existing clients' proselytizing, which has spread Boomtown's base across 49 states and into Canada.

Allen has a strategy to continue its meteoric rise but acknowledged "once you get into the larger numbers in terms of revenue, it starts to get pretty difficult."

S.C. companies on Inc. 500

South Carolina companies on the Inc. 500 list:

25. Wireless Communications (Retail) Greenville. Operates 38 Verizon Wireless locations in S.C., Ga., Ky. and W.Va. Had $22.9 million 2011 revenue and 6,591% three-year growth. 200 employees as of 2011. Founded in 2008.

96. Boomtown (Software) Charleston. Produces a web-based marketing systems for real estate professionals. $4.6 million revenue and 3,085% growth. 38 employees. Founded in 2006.

118. O-Matic (Software) Charleston. Develops software to eliminate manual processes and improve operational efficiency for nonprofits. $3.8 million revenue and 2,656% growth. 15 employees. Founded in 2002.

227. Resource Financial (Financial services) Columbia. Underwrites home mortgages. $7 million revenue and 1,601% growth. 49 employees. Founded in 2008.

228. Suzanne Evans Coaching (Education) Murrells Inlet. Offers seminars online and one-on-one coaching to women business owners. $2.4 million revenue and 1,615% growth. Six employees . Founded in 2007.

338. BiblioLabs (Media)Charleston. Publishes historical materials in digital formats and creates apps for cultural and academic institutions . $17.5 million revenue and 1,111% growth. 15 employees. Founded in 2006.

359. Dovetail Insurance (Insurance) Columbia. Provides services and technology to insurance carriers. $5.4 million revenue and 1,036% growth. 52 employees. Founded in 2006.