Basic cable has traditionally been something of the ugly stepchild of the television world, the place to see reruns of Seinfeld and old movies you were never that excited to see even when they were in theaters. And it certainly wasn't the place to see award-winning or critically favored original shows.

And yet when the Emmy nominations came out in July, the belle of the ball was Mad Men, a show that airs on AMC, a small cable channel known best, until recently, for packaging and airing classic American films like Casablanca and A Fistful of Dollars. Mad Men, which chronicles the lives of hard-charging ad execs in the early '60s, received the most Emmy nominations of any drama on either broadcast or cable this year with 16, and countless, breathless articles have been written praising the series and its attention to period detail.

While no one was looking, cable—and not just pay channels like HBO—have become the new network TV, the place to watch the most creative, talked-about, and addictive dramatic series. While ratings typically fall far short of broadcast hits, these original series deliver especially attractive audiences to advertisers and help to establish a valuable brand identity for their networks. And as they continue to siphon off broadcast audiences, it may well be difficult for the broadcast networks to ever recover.

The person responsible for finding and developing Mad Men for AMC, even after HBO and Showtime passed on it, is Christina Wayne, the channel's head of original scripted programming since 2005. And she says it's unlikely a show like it would ever have been developed at a broadcast network.

On cable, "stories take a longer time being told, they focus on character, and it's not procedural closed-end stories week after week," Wayne says. That greater creative freedom, she believes, helps explain the success of Mad Men and other new basic-cable series (see our head-to-head comparison of the programming chiefs at the major cable networks).

"The TV landscape has obviously changed," adds Charlie Collier, AMC's general manager, pointing out that the broadcast networks' focus on cheaper-to-produce reality programming and game shows have left the door wide open for the cable networks to establish themselves with high-end original programming.

Things first started to shift in 2002 when FX started airing its gritty police show The Shield, and then followed that up the next year with Nip/Tuck, its look at the unseemly lives of two plastic surgeons. Now, AMC is one of several basic-cable channels, including FX, USA, TNT, and the Sci-Fi Channel, that have joined premium-cable networks HBO and Showtime in rolling out original scripted series. More and more of the TV industry's creative energy—not to mention critical acclaim, A-list stars, and ad dollars—are now on cable.

And the change seems to suit audiences just fine.

"Viewers are increasingly not differentiating between the Big Three and the Big 300 channels they have on their cable systems," says John Rash, senior vice president and director of media analysis at Campbell Mithun, an ad agency based in Minneapolis.