John Scalzi, Old Man's War
John Scalzi had a wildly successful blog first, and his fiction career only came later. Scalzi was a professional author long before penning Old Man's War and several other hits of the decade. As one of the earliest wave of professional bloggers, he successfully built up an audience for his blog, which also happens to be where he archived copies of his then-shareware (now-freeware) book, Agent to the Stars.
Old Man's War is military science fiction for grown-ups. Scalzi takes real people - older people; in a word, grown-ups - and inflicts far-flung world-building wars upon them. The result is a clear headed look at mortality, the process of aging, and the ethics of war.
Although many crotchety members of science fiction's "old guard" paint John Scalzi as an upstart blogger who somehow fell into a publishing contract, his is more a story that "talent will out." Scalzi's popularity as a blogger may have been what first caught the industry's eye, but it was his talent as a writer that kept him there.
Scott Sigler, EarthCore, Ancestor, and Infection
For better or worse, Scott Sigler has undoubtedly made a name for himself in the history of contemporary American fiction. Sigler's first novel EarthCore was first self-published as an eBook. He later began podcasting the novel in installments through iTunes, where he gained a significant following and a considerable amount of buzz for being "the world's first podcast novel."
Sigler released his subsequent novels as "podcast novels" as well. (I listened to Infection and was generally unimpressed, although it has since been optioned as a movie.) At the same time, Sigler worked hard to become seemingly ever-present on science fiction blogs and podcasts, most notably the esteemed science fiction podcast Escape Pod.
Cory Doctorow, Down and Out in the Magic Kingdom
Again for better or worse, if this decade can be marked by any persona, it would be Cory Doctorow. Doctorow never met an adjective he didn't like, and his enthusiasm frequently overruns his skills. Nevertheless, Doctorow has been a tireless advocate for digital freedom, open source software, and projects like Creative Commons. In fact, his 2003 novel Down and Out in the Magic Kingdom was the first novel to be released under a Creative Commons license.
At about the same time he seemed to be gradually taking over Boing Boing, as if attempting to single-handedly bank as much "whuffie" in as short a time as possible. Down and Out in the Magic Kingdom has many faults, not least of which being a tin ear for coining terms like "whuffie," which is a reputation system that (in Doctorow's imagined future) replaces the concept of money. (It is perhaps one of life's enduring mysteries why a noted open source fanatic should be so enraptured by Disney, the most closed-source company in all of human history.)