Nathan Seidle

From his college apartment, Nathan Seidle (ElEngr) built and sold his first circuit boards. Twelve years later his company, SparkFun, sells 100,000 circuit boards a month, offers 2,000 different products and has annual revenues of nearly $33 million. This summer SparkFun opened its first offline store in Niwot, Colo., catering to small-scale buyers interested in kits and parts.