Similarly, Michael Wright, who oversees original content for TNT, TBS, and TCM, three of Turner Broadcasting's six cable properties, says that the economics of developing a hit show on broadcast become much more difficult with so much competition and splintering audiences.

"In a 300-channel universe, if your business model is based on aggregating 10 to 15 million viewers [a week] to achieve success, that's tough," Wright says.

From Wright's perch, however, the world looks grand. TNT's The Closer, starring Kyra Sedgwick, is averaging well over eight million viewers per episode this season, making it the top-rated show on cable and rivaling even some broadcast hits for ratings. Saving Grace, another breakout TNT original, starring Holly Hunter, averages 4.6 million viewers.

Some of AMC's original creations have been even bigger in the ratings. The first script Wayne developed for AMC was Broken Trail, the network's first original miniseries, starring Robert Duvall in a revisionist Western. The series aired in 2006 to an audience of 9.7 million, making it the second-highest-rated basic-cable-network miniseries of the previous 10 years.

When Broken Trail was being developed, Wayne was the only staffer in the original-programming department. The network was looking at original programming as a way to differentiate itself and produce cinematic content that was consistent with its focus on classic movies (Mad Men, as well as several other AMC original shows, is actually shot on film, which is unusual for a television show). As soon as Broken Trail became a hit, Wayne had a mandate to develop more shows.

Today, Wayne has a staff of seven and is juggling a development slate of 30 series and miniseries. She's now several weeks into production on the network's next miniseries, The Prisoner, which stars Sir Ian McKellen and Jim Caviezel and launches in the summer of 2009.

"What we wanted to do was link up with the movies that we have and provide programming that was cinematic," she says. "If we can give viewers that one-hour movie experience every single week, it provides destination viewing."

Indeed, because they create viewer loyalty and help cable channels establish brand identities, original scripted shows are often an excellent investment. "You can go spend $20 million on billboards to sell the network, but a hit show does that for free," says Turner Broadcasting's Wright.

Of course, original programming is far from free, often costing tens of millions of dollars to develop and produce a new series. But Wright's point is that, aside from generating advertising revenue, hit shows help to call attention to a network and its other programming as well.

"You get that halo effect" for the network, says Steve Kalb, senior vice president and director for broadcast media at MediaHub, ad agency in Wenham, Massachusetts.

And cable networks, with less hours of original programming to fill, have an important advantage over the broadcast networks. They can get away with ordering only 8 to 15 episodes for a season, which translates to a shorter filming schedule that is attractive to top-quality actors. Broadcast networks typically order as many as 25 episodes per season.

And once a hit show is established and viewers increase—even if the ratings were small to start off with—the investment pays dividends as advertisers come flocking.

Mad Men, for example, averaged just under a million viewers per episode after it debuted last summer. Four episodes into the new season, it's averaging 1.4 million. Though the audience is small compared to broadcast hits that average many times that number, it's a strong increase and one that advertisers have responded to. And AMC has successfully pointed to the classic films in its library, leading into the premiere of Mad Men with a highly-rated showing of classic gangster movie Good Fellas and running a month of films about antiheroes to go with another original show, Breaking Bad, that led to the network's highest-rated month ever.

For Wayne, it's not a surprise that Mad Men has gotten the attention and accolades it has, despite some initial concerns that viewers wouldn't respond to a period 1960s drama.

"We always felt that if it was something that connected in some way to us and resonated with us, it would be a fit with the channel," Wayne says.