FORTUNE — Steve Yankovich didn’t expect to find inspiration in a romantic comedy. The vice president of eBay Mobile remembers watching Something’s Gotta Give in 2003, and falling in love with a sleek toaster that he noticed on Diane Keaton’s counter. He searched a few stores for the toaster, then broke down and called the studio. The hunt, recalls Yankovich, made him feel like a “crazy person” for wanting a household appliance so badly.  Fast-forward a decade. Yankovich still hasn’t found the toaster— but the experience helped trigger a new way of connecting shoppers with the products they see on-screen. After years of failed efforts by media and tech companies, eBay and others may be making “couch commerce” a reality, merging the classic American habits of watching TV and shopping. In March eBay EBAY launched “Watch with eBay,” an iPad app that serves up eBay listings related to the shows users are watching on TV. Yankovich wants the app to spur impulse buying— good for a company like eBay, which gets a cut of every sale. “When it’s on the top of people’s mind and convenient to them, that’s when they buy,” Yankovich says.  For years television-based buying — or “T-commerce”— has been limited to late-night infomercials and shopping networks like QVC. In the early days of e-commerce, technology was so nascent that people couldn’t watch, surf and shop at the same time. To search for an item online, a TV viewer had to get up, connect a cable, and dial up the Internet, all the while missing precious minutes of his favorite show. If a viewer waited until a program was over, he’d forget what he wanted to buy.  MORE: Why the new iPad launch drew such short lines in China  But thanks to the growing popularity of iPads and other tablets, T-commerce may soon gain traction. According to a 2011 Nielsen study, more than 80% of U.S. tablet owners have used their device as a second screen. Wireless technology has made it possible to glance something in a TV program or commercial, and after a quick search, buy it instantly online.  Companies like eBay want to streamline the process further. To shop on Watch with eBay, users enter their zip code, cable operator, and the show they’re watching. An outside company gives eBay a list of keywords— like the name of a sports team or an actor— that it associates with a show. The app’s internal search engine scours eBay’s inventory for those keywords, and then displays a grid of related auction items. A golf fan watching the U.S. Open, for example, can bid on the same cap that Bubba Watson wears while he tees off.  Yankovich says that eBay has “tens of thousands” of items in a particular category, like sports memorabilia, shoes or cars. But he’s tight-lipped about whether people are actually using the app, or whether it’s had any impact on eBay’s sales.  Smaller tech companies are also trying to break into T-commerce. Next month WiOffer, a digital advertising startup in New York, is releasing an iPad and iPhone app that uses the sound from a TV to give viewers discounts and promotions. If you’re watching “30 Rock,” you might see an ad for a new movie during a commercial break. WiOffer’s app will hear that commercial and within seconds, serve up four different “activity” buttons on your handheld device. One “button” might be a link from the movie studio, allowing you to buy a discounted ticket. Another could be a Google map showing you where the movie is playing.  MORE: What YouTube can learn from Youku  Marketers tell WiOffer which “activities” the app will promote, and gives WiOffer a copy of the commercial before it airs. WiOffer then takes the sound from the commercial and uploads it into the server. The app can later recognize the commercial on TV.  WiOffer co-founder Andrew Pakula says that the year-old startup has landed 15 clients. (He won’t disclose whom.) Marketers will pay WiOffer every time the app delivers promotions to users.  Couch commerce may be good for brands and tech companies, but it could also change the way people experience home entertainment— for the worst. Young viewers are already tech multi-taskers, texting and surfing the Web while they watch TV. Shopping is yet another distraction. “You don’t want to break up a movie to sell sunglasses,” says Jay May, who runs the Feature This product placement agency. “I would never do anything to hurt its integrity.”
New technology allows TV viewers to buy what they see on the screen -- without getting up from the couch.