The site, available on the CBS.com home page, is streaming three shows a day at first, at least one of them new each day. Material already shown will be archived and available for free to computer users.
"We want our content to be all the places our viewers are — and they are certainly on the Internet," said Nancy Tellem, president of the CBS Paramount Network Television Group.
Among the shows debuting this month: "Greek to Chic," a makeover reality series for college students; "BBQ Bill," a sketch comedy series with Rick Najera; "Animate This!," where celebrities narrate funny stories from their lives that are animated; and "Beyond Survivor," a behind-the-scenes look at the reality show.
CBS has moved to build its online presence in news and sports over the past few years, too.
NBC Universal offers video content on its networks' Web sites now, including news programs like "Today" and "Meet the Press," and is planning to soon offer some original content. ABC News has a broadband channel that airs a preview edition of "World News Tonight" each afternoon.
Later this month, "innertube" will begin streaming "Fire Me ... Please," a reality series that was canceled on the network last year before all of the episodes aired. Similarly, "innertube" will be the destination for episodes of the drama "Love Monkey" that were not aired before it was taken off CBS for low ratings.
When popular series like "CSI: Crime Scene Investigation" might be available is an open question. Tellem said CBS is discussing the issue with its local affiliates, which are nervous about anything that might encourage people to watch the programs anywhere but their stations.
CBS touted its library of more than 2,600 past TV series in announcing the venture, but its executives also said it's unclear when these old programs would be streamed on the Web.
CBS is selling advertisements on "innertube." Some of the series also contain product placement.
The network has been the most aggressive in exploring different outlets for its programming. Through Google Inc., CBS is selling episodes of its hit shows and classics like "The Brady Bunch," and is also renting episodes of "Survivor" through its own Web site.
CBS wants to experiment with as many options as possible to see which consumers gravitate toward, Tellem said.
"Innertube" is being looked upon as a way to familiarize young viewers with programming on CBS, still the network with the oldest audience. And it's a way to explore different creative ideas; if some work, they could find their way onto the TV network, she said.
"This gives us a whole new opportunity to develop new ideas on a platform that doesn't demand the high costs that we're seeing on the network side," she said.