TV networks are heading online in a big way, as more and more begin to stream their shows over the Web for eager viewers. Now the SciFi Channel, owned by GE (NYSE:GE) and Vivendi's (NYSE:V) NBC Universal, is going one step further. For the first time, online viewers will help determine whether a proposed new show gets the network's approval.

A full two weeks before it premieres on SciFi's airwaves, the pilot episode of The Amazing Screw-On Head is streaming exclusively on SciFi Pulse, the network's broadband video service. The animated series, based on Mike Mignola's comic book, stars Oscar nominee Paul Giamatti as a robotic secret agent in the employ of Abraham Lincoln, battling 19th-century menaces with the aid of an assortment of interchangeable bodies. After watching the pilot, viewers are directed to an online survey, where they can provide SciFi with basic demographic information, their opinions on the characters, and their likelihood to recommend the show to friends.

Given Screw-On Head's bizarre premise, quirky humor, and big-budget voices and visuals, it's no surprise that SciFi would hesitate to spend millions of dollars on an entire season. But rather than simply air the pilot and cross their fingers, SciFi executives are smartly using the Internet to gauge viewers' interest -- and perhaps build a fan base before the show ever airs.

SciFi's no stranger to Internet video, having previously promoted its hit revival of BattlestarGalactica by streaming sample episodes to online viewers. Old-fashioned NBC has similarly embraced online video, including a pact with the YouTube video-sharing site to spread NBC clips across the Internet, and original online "Webisodes" of its hit comedy The Office. Viacom's (NYSE:VIA) Comedy Central and Time Warner's (NYSE:TWX) Adult Swim are now showing episodes online, and Disney (NYSE:DIS) recently concluded a two-month test of ad-supported online episodes of Lost and other popular series. And all the major networks now offer select shows for download via Apple's (NASDAQ:AAPL) iTunes service.

YouTube may even have helped to revive an innovative sitcom pilot that was left for dead in 2004. Both NBC and the WB originally passed on Nobody's Watching, a mock reality show about two friends from Ohio who are given the chance to create the perfect sitcom. But the show, from the creator of Scrubs and two Family Guy writers, has become a grass-roots hit since it mysteriously appeared on YouTube in mid-June. Now, according to a recent New YorkTimes article, its popularity online has reawakened networks' interest, giving the show another shot at prime time.

With an ever-increasing number of shows and channels -- and the Internet itself -- fighting for potential viewers' attention, networks are finding it increasingly difficult to build an audience for new series. Until now, they've largely ignored the Internet's potential to transform indifferent viewers into fans of shows they might otherwise never spot in the TV listings.

Whatever the fate of The Amazing Screw-On Head, I wouldn't be surprised if more networks began giving prospective series an online tryout before choosing their prime-time lineup. It's a smart idea that could cut marketing costs, provide networks with ad-revenue-boosting demographic information, and best of all, give viewers the kind of shows they really want to see.

At last, it seems, someone in the TV business has their head on straight.

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Fool online editor Nathan Alderman will spare you any further "head" puns. He holds no financial position in any companies mentioned above, though he does watch their networks. The Fool's disclosure policy is a hero for any era.