Small Davids | Fortune

Shoplet vs. Staples

The challenge: Taking on Staples (SPLS), Office Depot (ODP), and an army of smaller office-products stores. What he did: Tony Ellison, 44, knew it seemed crazy to ditch his career at Goldman Sachs (GS) to jump into the ultracompetitive office-supply market back in 1994. But with online commerce taking off, he couldn't resist and soon plowed his savings into opening Shoplet. "The big boys in the industry were very slow to move online," he says. It turned out to be a smart bet. Ellison's secret? He lured customers with more than 400,000 products -- and plenty of eco-friendly ones. He also made it easier for them to manage their office-supply spending by offering free proprietary electronic-procurement software. Today Shoplet brings in "nine-figure revenues" and employs 63 people in New York. Who needs a Wall Street career?

Moguldom Media Group vs. BET (VIACOM)

The challenge: Can a startup take on venerable brands to grab a share of the African-American media audience? What he did: When Jamarlin Martin launched the black-oriented gossip site Bossip in 2006, the former paralegal was surprised that so few media companies targeted younger (ages 24 to 40) African-American women. "I didn't see anyone saying this is a big opportunity," says Martin, 34. Thanks to dish on celebs like Tyra Banks and a mobile-friendly platform, Bossip took off. Martin soon spun out five other lifestyle sites, from MommyNoire (for new moms) to Hip-Hop Wired (for music lovers). Focusing on building traffic by obsessively studying the web-surfing habits of his readers, Martin snagged big advertisers like P&G (PG) and Starbucks (SBUX). Today his 45-employee company generates revenue of $11 million a year, he says. Next: a 24/7 video channel.

SoftLayer vs. Amazon Web Services

The challenge: Simply put, Amazon, Salesforce.com, and every other 500-pound gorilla in the cloud-computing universe. What he did: Lance Crosby knew he was onto something when he co-founded SoftLayer, a provider of cloud-based computing infrastructure, seven years ago in Dallas. Companies loved the idea of managing their IT resources, like servers, through SoftLayer's global platform instead of having to buy them on their own. Unfortunately, he wasn't the first to think of the idea: Amazon Web Services got rolling around the same time. To stand out, Crosby, 42, focused on attracting sophisticated customers like mobile-app developers, rather than Amazon's broader audience. Last year the profitable, nearly 700-employee firm logged $330 million in revenue. Crosby says, "Currently the cloud is growing so fast that it's a land grab at this point."