The woman who helped build cable's USA into the set-top-box powerhouse that it is today is setting her sights on other media fiefdoms.

When Comcast took over a controlling interest in NBC Universal, Bonnie Hammer, chairman-NBCU Cable Entertainment and Cable Studios, found her responsibilities greatly augmented. In addition to USA, SyFy and other properties, she now has two more channels -- E! and G4 -- from the Comcast side of the equation in her portfolio. Advertisers will be watching to see if she can do for those networks what she has done for others under her purview.

At present, she said, E! is known for news and reality programming and celebrity buzz, but "it's not really tied together, and doesn't have that crisp definition" that some other networks do. Under her aegis, she suggested, that 's about to change. "E! will have that advantage of a very specific and well-defined brand filter."

Ms. Hammer's plans are not to be dismissed. The casual observer may be shocked to realize that USA may now carry more importance to NBC Universal than its flagship broadcast network. (With its nearly $1.1 billion in ad revenue in 2010, USA brought in more ad dollars than the CW.)

While broadcast needs to play to the biggest crowd possible, cable outlets need to chase a distinctive but broad niche, then dominate it. That's where Ms. Hammer, 60, comes in. "What I tend to bring to something, that 's helping people to come to a really sharp focus of who they are, where they are and where they can get to."

As advertisers have come under economic pressure during the recession, many media companies have worked harder to define their audiences. Scripps Networks' Fine Living network was recast as the Cooking Channel, and News Corp.'s Fox Reality Channel was made into the fauna-focused Nat Geo Wild. At a time when more cable systems are putting more emphasis on direct-to-consumer applications such as video on demand, programmers need to prove their channels tap a viable audience that isn't easily duplicated elsewhere.

She has accomplished such tasks before. USA was once better known for shows such as "Silk Stalkings" and "Up All Night." Under her eye, it has become a place for character-driven dramas that typically focus on a put-upon protagonist who usually triumphs by the end of an hour. Whether the show is "Royal Pains" or "Covert Affairs," USA's offerings are easy to understand, if not always easy to differentiate from one another. Now she will turn her skill set on E! and NBCU's emerging set of entertainment networks, including Chiller, Sleuth (soon to be renamed "Cloo") and G4.