1. Netscape Navigator (1994)
Marc Andreessen may have known what he was getting into when he cowrote Mosaic at the National Center for Supercomputer Applications, but it wasn't until he graduated from college and met with some Silicon Valley types that the Web revolution really began. In 1994 Andreessen launched Netscape Communications, offering his new Navigator Web browser (based on Mosaic) to the world. Finally, users outside of the academic world would get a taste of HTML, and nothing has been the same since.
Netscape was the reason people started spending hours a day on the Internet, leading to the boom (and bust) of many a Web site. The advent of the browser also led to the U.S. Department of Justice's antitrust suit against Microsoft, after the company embedded Internet Explorer into Windows. And Netscape's August 9, 1995, IPO is universally considered to be the official start of the dot-com era.