Adan Canizales suffers from TV gridlock.

Three of his favorite shows -- "The O.C." on Fox, "Scrubs" on NBC and "Grey's Anatomy" on ABC -- all aired on Thursday at 9 p.m. this past fall. So Mr. Canizales, a New York University law student, devised an elaborate solution. He watched "The O.C." on TV and recorded "Scrubs" on his TiVo digital video recorder. But since his TiVo can't record two shows at once, he later opened his laptop to watch "Grey's Anatomy" online.

"There is no way I could watch all of them at the same time, even with TiVo," he says.

Last year was the year the television networks took the plunge and allowed some of their programs to be available online, free. They didn't want to end up like the music industry, which initially fought the Web and suffered from decreased sales. What's more, TV networks saw customers fast-forwarding through commercials on their DVRs and wanted to provide a format where they couldn't zap the ads.

But networks are still gauging how audiences are responding to online programming. Currently, most Web offerings are delayed between an hour and as much as a day after they are aired on TV. And advertisements, which might differ from those that appear on TV, aren't skippable.

"Everything is untraditional in this new space," says Vivi Zigler, executive vice president of NBC Digital Entertainment and New Media, an NBC unit that seeks out new ways to reach consumers. "You put something out there, and see how people respond."

It's too early for real ratings data: ABC, which is owned by Walt Disney Co., for instance, says it had a total of 30 million "starts" last fall on its full-episode Web programming, meaning viewers who at least clicked on a show at the beginning. Considering that ABC was measuring eight prime-time series, over a period of three months, the result was tiny compared with regular TV. The network's "Desperate Housewives," for instance, had 17.9 million viewers for a single episode this week. What's more, ad revenue from online programming is small.

But viewership is growing -- mostly among tech-savvy young people who like the convenience of watching a show anytime without having to record it. "While it's still early, it's clear that there is a demand for (online) video," says Albert Cheng, executive vice president of digital media for Disney-ABC Television Group. "There is an audience for our shows and it is an effective vehicle for advertisers to reach our customers."

For now, online viewing can be confusing, as each network has its own system. ABC, General Electric Co.'s NBC and News Corp.'s Fox, for instance, offer a handful of programs on their Web sites, whereas CBS Corp. makes almost all its prime-time lineup available. Also inconsistent are the timing of when shows are updated with new episodes and how long they remain available online.

Even finding the shows can be a chore. Most networks let people click to watch from their Web sites, although each site has the button in a different spot. Fox programs, however, aren't available directly on www.fox.com. You have to go to MySpace, the popular social-networking site owned by News Corp., or to certain local Fox station sites. But watch out: The MySpace home page doesn't have a button pointing to the Fox shows; you have to go to www.myspace.com/fox.

And for some people, watching the videos online hardly compares with sitting on a couch and enjoying a program on TV with friends or a bowl of popcorn. Michael Hickerson, a state government employee in Nashville, Tenn., watches several shows online, including NBC's "Heroes" and "Friday Night Lights," but makes it a point to tune in to ABC's "Lost" when it airs on TV. "In my circle of friends, everyone is talking about it the next day," Mr. Hickerson says. "I want to be part of that water-cooler buzz."

The Web TV audience soon can expect an expanded lineup of shows and Web-exclusive programming, as well as more interactive components, like blogs and games. This past fall, NBC featured a "producer's cut" of "The Office," providing eight additional minutes of content that weren't available on TV. Fox offered special pre-TV debuts for "The O.C." and "The Simpsons." The cable networks also are testing the field: MTV streamed the season finale of "Two-A-Days," a series about high-school football, on MTV.com before airing it on TV. Networks also are experimenting with user-generated content and social-networking experiences.

Whether viewers want all these extras isn't clear. The networks' early research shows that Web viewers are mainly ardent fans of shows that they can't always catch on TV. Kevin Elwell, a junior at University of Central Florida, is a self-described "Lost" addict. "Once I got into it, I couldn't miss it," he says. But this fall he was stuck in a business class on Wednesday evenings, when the show aired. Instead, he arranged to watch it online later with a friend who also had classes to attend during the broadcast.

But if you're a fan of "E.R.," you're out of luck. The reason: NBC doesn't own the show and is limited by licensing agreements with Warner Brothers, which makes the program and owns the Internet rights. Networks that have more flexibility with the licensing of their shows, such as CBS, offer more of their lineup online.

All of the networks say they're pushing to add more -- both in terms of the number of series and episodes -- to their online offerings. Still, some shows like "The Simpsons" haven't been made available, even though they're owned by the company that airs them.

Here's a network-by-network guide to online viewing:

ABC: Eight ABC series, including "Desperate Housewives," are available at ABC.com. Another series, "Ugly Betty," is sponsored by Brita LP, the filtered-water company. Each show is divided into four segments separated by 30-second, interactive Brita ads after which viewers must click to continue watching the episode.

CBS: Full-length episodes from 13 different CBS series are available on its "Innertube" ad-supported broadband channel, at www.cbs.com/innertube/. The number of episodes available for each series varies from about a dozen for high-profile shows like "CSI," "Jericho" and "Survivor," to only recently aired shows for some series like "Shark" and "The Unit." Shows are separated into sections by nonskippable ads, and links are included to email the video and visit the series Web site.

Fox: Fox on Demand introduced free, ad-supported shows this fall to its www.myspace.com/fox page and on MyFoxLocal station sites in 24 markets. Viewers can stream previously aired episodes of eight shows, including "Prison Break" and "Bones," which are updated after their TV broadcast. Some popular shows like "The Simpsons" and "House" aren't available, although a seven-minute preview of "The Simpsons" drew 1.4 million hits over three days in September. The MySpace site also provides interactive options, with links to the show's official site.

NBC: Full episodes of six NBC shows, including "30 Rock" and "Friday Night Lights," are accessible on its NBC Rewind video-streaming site at www.nbc.com/Video/rewind/. Like the other networks, shows are divided into segments by nonskippable ads. Every full episode is available for some shows, such as "Heroes." But some of NBC's most popular series, such as "The Office," "Scrubs" and "E.R.," aren't offered, other than in two-minute replays.