The Sopranos: The series people will most associate with the decade, by virtue of its having invented the quality-cable brand.
Sex and the City: Spiky, poignant, rewatchable—and I suspect humans will still be overanalyzing breakups in ten years.
American Idol: Of all the reality shows, this is the one that changed not just TV, but the music industry and the nature of stardom itself.
The Daily Show with Jon Stewart and The Colbert Report: The outraged court jesters of the Bush years, they reinvented the way people get—and analyze—their news.
The Oprah Winfrey Show: The dominating pop-culture personality, she transformed herself into a multi-platform portal for all things self-improvement.
Lost: It will be remembered as oh so very aughty, but nobody will remember why they were so obsessed with that damned hatch.