NEW YORK (CNNMoney.com) - There has been a lot of chatter about how network television is starting to lose some of its allure thanks to the growing popularity of online video and digital video recorders that allow people to fast forward through ads.

But there is another reason why networks may be struggling in their fight to attract the attention of both viewers and advertisers: cable. Last year, cable ad revenues were up more than 10 percent. And according to TNS Media Intelligence, an advertising research firm, cable TV ad revenue is expected to increase 6 percent this year, matching the expected ad sales gains for network TV.

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While the major broadcast networks largely take the summer off, mainly showing reruns and some new reality shows, basic cable is increasingly viewing the summer as an opportunity to launch original scripted dramas that tend to be edgier than what's on regular network TV.

And people are tuning in, partly due to the fact that many basic cable shows are receiving a large amount of acclaim from TV critics.

"Viewers are interested in good programming wherever it may be. And awareness of the best cable shows has increased because of positive critical reviews," said Shari Anne Brill, vice president and director of programming with Carat USA, a media buying firm.

Many cable shows are putting up pretty respectable numbers. The second season premiere for TNT's "The Closer" averaged 8.3 million viewers, according to Nielsen Media Research, a record for a scripted basic cable series. (TNT is owned by CNNMoney.com's parent company, Time Warner (Charts).)

USA's "Monk" routinely averaged more than 5 million viewers an episode during its latest season. Its new season debuts next month.

And FX's "Nip/Tuck" is also a bona fide basic cable hit. Its third season premiere in September 2005 was watched by nearly 5.3 million viewers and subsequent episodes last fall pulled in about 4 million. The show is returning this September.

Robert Riesenberg, president & CEO, Full Circle Entertainment, a television programming producer owned by ad agency Omnicom, said one reason cable channels have been able to develop more hits lately is that they don't have to worry about producing nearly as many shows as the networks do.

"Advertisers tend to flock toward success. And cable networks can give shows tender loving care and spend more time developing characters and scripts," he said. "Plus they can throw so much marketing behind one or two shows as opposed to twenty."

Granted, even the biggest cable shows don't generate the types of ratings that even mildly successful network TV shows do. For example, ABC's "Boston Legal," which finished the just-ended prime-time season in a tie as the 46th most watched program, averaged more than 10.6 million viewers an episode.

But for advertisers, experts say cable offers a more effective way to reach a specific audience.

"It's unequivocally the case that niche shows with smaller audiences are better," said Bill Abrams, a partner focusing on entertainment and corporate law with law firm Abrams Garfinkel Margolis Bergson, LLP.

"The broadcast networks are not a terribly efficient way for marketers to reach people. Certain advertisers can hit the exact markets they want at a lot lower cost," he added.

To be sure, most of the big media companies have been able to benefit from the emergence of cable even as their broadcast networks battle for ad dollars. GE's (Charts) NBC Universal unit owns USA, Sci Fi Channel and Bravo. Walt Disney (Charts), in addition to ABC, owns ESPN and Disney Channel. News Corp. (Charts), the parent of Fox, also owns FX.

The only top TV firm that lacks a significant basic cable presence is CBS (Charts). CBS owns premium cable network Showtime while Viacom (Charts), the company CBS split from earlier this year, owns basic channels MTV, Nickelodeon, Comedy Central and BET.

But Tim Spengler, executive vice president and director of national broadcast with Initiative, a media buying firm owned by ad agency Interpublic, said that cable is starting to suffer from the same problems that plague the top broadcasters.

"Advertisers are continuing to try and communicate to target audiences through the most relevant way," said Spengler. "That does lead you to more niche offerings but niche offerings are not restricted to traditional media. More money is also going to niche offerings on the Internet."

Carat's Brill said cable has another thing working against it. The very thing that makes some shows popular, i.e. racier content, may scare off some advertisers.

At the end of the day, Spengler said that, like with regular prime-time broadcast TV, cable will have its share of winners and losers. He said networks like TNT and FX, which have had several original hits, could score with marketers.

The key, of course, is developing programs that will resonate with viewers. And that's easier said than done.

"Getting it right is harder than ever in a world with so much media and a more than 100 channel universe. But anything can easily be monetized when you have a hit. The sky is the limit," he said.

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The reporter of this story owns shares of Time Warner through his company's 401(k) plan.