(FORTUNE Magazine) – Frank McNamara

McNamara claimed that the credit card was born when he ran out of cash at a restaurant; his wife had to drive two hours to bail him out. The story may be apocryphal, but McNamara's 1950 invention, the Diners Club card, is the forebear of today's credit card industry.

Edward Roberts

In 1974, Roberts' company, Micro Instrumentation & Telemetry Systems, unveiled the Altair, the first personal computer. Named for a planet from Star Trek, it couldn't do much, but it launched the software-writing careers of, among others, Bill Gates and Paul Allen.

Benjamin Holt

Holt's invention, the gasoline-powered tractor, revolutionized agriculture, freeing farm machinery from its dependence on horses. It received its name when, during the first test run, an onlooker commented that it moved like a caterpillar. Hence the Caterpillar Tractor.

James Casey

In 1907, at age 19, Casey founded American Messenger Co., a bicycle delivery service in Seattle. A few years later the company had its first truck and a new name: United Parcel Service. Switching from bikes to trucks was a smart move; the company delivered three billion packages last year alone.

Narinder Kapany

In high school, a teacher told Kapany that light could travel only in a straight line. Kapany set out to prove him wrong and wound up creating fiber optics, the technology behind devices ranging from endoscopy to high-capacity telephone lines.

Henry Kaiser

Kaiser built a conglomerate encompassing everything from shipbuilding to cement. So why have you never heard of him? Simple. He didn't train a successor. Within 21 years after his death, all the Kaiser companies had either been sold or gone under.

Marriner Eccles

He's little remembered today, but Eccles, a bank owner from Utah, served as Fed chairman during the crucial years from 1934 to 1948. He also helped write the Banking Act of 1935, which gave the Fed greater independence--setting the stage for the pop phenomenon that is Alan Greenspan.