Digital cable subscribers have become accustomed to watching their favorite cable shows on demand, but now whole networks are springing up that are only available as video on demand. They have no dedicated channel position -- no "linear channel," in cable parlance -- no Channel 340 with 24 hours of programming, for example.

This latest generation of cable networks is even more niche-oriented than their linear channel forerunners (Sci Fi Channel, Food Network). Diane Robina, a former MTV Networks executive who is now president of Comcast Emerging Networks, calls them "superniches."

Earlier this year, Comcast began carrying Shalom TV, a Jewish cultural network. Other VOD-only networks on Comcast include Exercise TV and FEARnet, a horror movie channel that launched in late 2006. Digital cable customers can access these channels through the on demand menu on their cable remote controls.

"It is certainly the wave of cable television's future," said Shalom TV president Mark Golub of VOD networks. "But I would be silly to say it would be my first choice."

Having a set channel number remains the goal for many networks, but cable operators have other priorities.

"It's very hard for cable operators at the moment to give up bandwidth because they're in an enormous fight with satellite for high-definition channels," Golub said. "They're trying to increase the number of HD channels to compete with DirecTV and EchoStar."

Jake Steinfeld, founder of Exercise TV and known for the Body By Jake line of fitness equipment, launched the linear channel Fit TV in 1993, selling it in 1998. When he created Exercise TV in 2006, he had to "check my ego at the door" with regards to VOD.

"Once I understood it, I said, 'Holy smokes, fitness is born for on demand and on demand for fitness," Steinfeld said. "The consumer is the boss. You watch your program when you want to watch it."

Some VOD channels include commercials at the beginning of shows. Exercise TV integrates sponsor messages into the program content. Shalom TV is still working on adding sponsorships to its shows.

Because these are non-linear networks, it's sometimes difficult to discern when new shows will be posted. Shalom TV, available in 15 million homes nationwide, adds about five new hours of programming every Sunday. Shalom TV's kids' show, "Agent Emes," is filmed in Pittsburgh with familiar scenes of Squirrel Hill and the Cathedral of Learning in its episodes.

"Emes" was created by Squirrel Hill's Leibel Cohen, who has filmed five episodes starring his son, Sholom Ber Cohen, as Agent Emes since 2003 when Sholom was 10. Now that he's 15, Leibel has begun a search at Agent-Emes.com. for a new actor to play the young Jewish crimefighter.

In addition to "Emes," Shalom TV has other Pennsylvania connections: Chief marketing officer David Brugnone, who previously worked for KBL Sports Network (forerunner to FSN Pittsburgh), works out of his home in Harmony, and Shalom TV chief operating officer Bradford Hammer helped build the Pennsylvania Cable Network.

For FEARnet, VOD is the perfect platform, Robina said, noting the love of horror films among young viewers.

"VOD is really good, especially for millennials, viewers who are 12 to 34 years old," she said. "The under-40 set wants to watch what they want when they want it. They listen to music from iTunes, they pick their songs, and they pick their programming on VOD."

Even for the older-skewing Shalom TV, VOD has worked out better than Golub expected.

"I am both surprised and impressed by the demo that does use VOD," he said. "It's a much wider demo that includes an older population than I thought would be involved."

But getting the word out remains a hurdle.

"The biggest single problem is, how am I found? You don't find me by channel surfing," Golub said.

Exercise TV has crossed that hurdle by partnering with advertisers to spread the word in exchange for product integration in Exercise TV shows. FEARnet has a Web site, FEARnet.com, that streams movies and drives horror fans to the on demand channel.

FEARnet, Exercise TV and Shalom TV are all free to digital cable subscribers, but there's another business model for some VOD channels: Subscription VOD.

Comcast also carries Here!, a premium VOD channel that targets gay viewers and is available in 50 million homes. A subscription costs $7.99 per month and gives subscribers access to 40 hours of programming monthly with 10 hours refreshed each Friday.

Unlike the linear digital gay network Logo, which relies heavily on reality shows, Here! has made original scripted programs its priority, debuting the series "Dante's Cove" and "The Lair" and upcoming original movies "Shelter" (April 18) and "Kiss Me Deadly" (May 2).

"When people think of HBO, they don't think of cheap reality shows," said Here! founder and CEO Paul Colichman. "We are being sold as a premium along with HBO and Showtime, so we need to deliver something that looks and feels premium to the consumer. In our minds, that is story-form content."

Future scripted series will be from the science-fiction, medical- and police-show genres.

"Gay spy, gay detective, gay doctor, gay lawyer," Colichman said. "Everything straight people have, we're gonna have."

NBC announced its fall schedule Wednesday, renewing "Lipstick Jungle" and "Friday Night Lights" but canceling "Journeyman," "Bionic Woman," "Las Vegas" and "Scrubs," which is expected to move to ABC for one last season. "Lights" will air first on DirecTV in the fall, joining NBC's lineup after the Super Bowl in early 2009. "ER" was renewed for a final 15th season.

NBC, which has been a ratings cellar dweller in recent years, will debut just four new series in the fall, including a new "Knight Rider" based on the recent TV movie. A series of "Saturday Night Live" political-themed, half-hour prime-time specials will air in October as "Thursday Night Live" in the 9:30 p.m. time slot.

In addition to more hour-long "Office" episodes in the fall, NBC plans an "Office" spinoff that will premiere after "Super Bowl XLIII." Details of the setting and which characters might migrate from "The Office" to its spinoff are being kept under wraps.

Among new series, there's a familiar theme: They're almost all remakes of known stories. From "Knight Rider" to "My Own Worst Enemy" ("Jekyll & Hyde") to "Crusoe" ("Robinson Crusoe") to "Kings (the Biblical story of David & Goliath) to "Merlin," NBC is all about escapist fare. Details on the NBC schedule can be found in Tuned In Journal at post-gazette.com/tv.

Celebrated Carnegie Mellon University professor Randy Pausch, who became an Internet sensation last year with his "last lecture" after being diagnosed with pancreatic cancer, will be interviewed by Diane Sawyer on ABC's "Primetime" Wednesday at 10 p.m. on WTAE.

On Sunday we launch a slightly revamped TV Week.

Readers still vexed by the deletion of overnight listings two years ago have reason to rejoice: The overnight listings return. To accommodate them, we've reorganized and consolidated the morning and afternoon grids. We've also added more prime-time highlights, and TV Week now includes prime-time listings for National Geographic Channel (NGEO).

One change that already occurred: A different crossword puzzle appeared in TV Week last month. Why? Because the company that provides the crossword puzzle is phasing out the old crossword and switched us to a different one. There's not much I or anyone at the Post-Gazette can do about that. Some readers don't care for the new puzzle, and we'll try a different TV-themed crossword in TV Week beginning April 13.

In this week's Tuned In Podcast, Post-Gazette entertainment editor Sharon Eberson and I discuss recent episodes of "How I Met Your Mother" and pilot season. Subscribe to the podcast or listen to it at post-gazette.com/podcast/.

This week's TV Q&A responds to questions about "Top Gear," "24," and WPCW in HD. Read it online at post-gazette.com/tv.