Google's Sergey Brin has an estimated net worth of $18.7 billion (US). (Forbes.com)The Internet boom put these 34 innovators on our list of the world's richest. Total worth: $109.7 billion (US).

In 1999, Marc Benioff was a high-paid executive at Oracle and ready to move on. He explained to a reporter he would rather work for himself than another "billionaire S.O.B." Now he is one.

A billionaire, that is. He spotted an opportunity in the business of managing customer relationships. At the time, a business that wanted a computer application to manage customers faced a long and expensive ordeal. The business needed buy customized software, pay for hardware to run the programs, and then shell out even more money to the software company for installation and maintenance.

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Fine for a mega-cap company that could drop a few million dollars without blinking, but it shut out small businesses. So he built Salesforce.com, which offered a new way to manage customer relationships. Its product was simpler and cheaper than tailored software. By providing the service over the Web — eschewing installation and maintenance fees — Salesforce could charge as little as $50 per month.

"Salesforce took off with largely smaller businesses," says Andrew Waldeck, a partner at the Innosight, a consulting firm specializing in innovation. "Those customers weren't attractive to the incumbent, because they couldn't service them profitably. Salesforce could."

Feeding off its bases of small businesses, Salesforce was able to continue improving its product and capabilities. Soon, the firm was grabbing the coveted mid- and large-size customers. By 2004, it boasted clients like Cisco, Staples and Advanced Micro Devices.

Disrupting the marketplace

Forbes valued Benioff's net worth at $1.2 billion in March. He joins 33 other men and women on our list of the world's richest who owe much of their success to Web sites or online services, to the tune of $109.7 billion in total net worth. Most have products that were highly disruptive to the marketplace.

A common element among disruptive innovations is that they satisfy a group of overlooked consumers. To find one of these groups, Pierre Omidyar didn't need to look any further than his fiancée: She was an avid Pez-dispenser collector who couldn't find a place to buy or sell pieces for her collection.

Omidyar, a computer programmer, built a Web page called eBay that could do that job for her. He charged a quarter per listing to other hobbyists, and soon needed to hire somebody to open up all the checks piling up at his home.

"EBay figured out way to reduce transaction costs and create a market around low-cost collectibles that people previously didn't have the opportunity to trade," says Waldeck.

Millions of Beanie Babies and baseball-card auctions later, Omidyar is another Web billionaire. Forbes valued his net worth at $7.7 billion in March.

He's joined on the list by a couple of his hired hands: The company's first full-time employee, Jeffrey Skoll, has a fortune Forbes estimated at $3.6 billion in March; former chief executive Meg Whitman has $1.3 billion.

Head of the class

Professor John Sperling spotted an underserved crowd in who was missing his classes. While teaching humanities at San José State, he concluded traditional schools of higher learning neglected non-traditional students. There were few classes that jived with the busy schedules of adults with jobs and families.

Sperling took the idea of his school for these non-traditional students to his employer. They weren't interested, so in 1976, Sperling founded the University of Phoenix, which is now a subsidiary of Apollo Group.

The first class had eight students. During its latest quarter this year, Apollo announced it had 345,000 students seeking degrees at its institutions. Much of the growth has come through the Web, where Apollo has been hosting classes online since 1999. Jeff Silber, an analyst at BMO Capital Markets, estimates that around 75 per cent of Apollo's University of Phoenix students are enrolled in online courses.

We estimated John Sperling's net worth at $1.7 billion in March. Like father, like son: John's son Peter also works at Apollo, and is on our list of Web billionaires with an estimated net worth equal to his father's.