Founder and CEO, O'Reilly Media
Why he matters: The man who coined the term "Web 2.0" has a talent for planting himself in the heart of the action. The Web 2.0 conferences produced by his publishing company, O'Reilly Media, have become the Internet industry's biggest business and cultural happening of the year.
Through his O'Reilly Radar blog, he is also one of the most influential voices in the world of open-source software. Not that he always gets it right: His proposal earlier this year to curtail bad behavior by creating a bloggers' code of conduct was met with scorn. But O'Reilly's ideas got the blogosphere chattering -- and, as always, he was smack in the middle of the conversation.