Fans of the TiVo digital video recorder have discovered how to break it open and install a larger hard drive. Early users of the Roomba, a robot vacuum cleaner, are rewiring it to serve as a "mobile security robot." Owners of the new Sony PlayStation Portable have figured out how to use the game machine to surf the Internet and exchange instant messages.
In the digital era, every consumer-electronics product comes with microchips and software programming, and for a new generation of tech-savvy users, these are the raw materials needed to make a digital toy or appliance do tricks that its creators didn't envision.
Sometimes, tinkerers become a consumer electronics maker's unofficial research-and-development team, with innovations winding up as built-in features down the line.
TiVo's most ardent fans came up with a way to record TV shows by sending commands via the Internet long before the company got around to officially offering that feature.
And before the iPod was the ubiquitous gadget it is today, early users of Apple's digital music player enabled it to store addresses and text files -- a feature the company now promotes.
Customers also came up with the idea of recording their own talk and music shows and making them downloadable for the iPod -- a phenomenon called "podcasting" that has become so popular that Apple recently rolled out software to streamline the process.
Americans have always liked to fiddle with things, from building better ham radios to juicing up car engines in the driveway. The urge fuels a multibillion-dollar industry in after-market auto parts, and automakers keep a close eye on how enthusiasts find new ways to use their products. Mitsubishi Motors, for example, sponsors teams that modify its Lancer Evolution performance car for auto shows.
For techies, the same instinct creates a drive to push the limits on anything that can conceivably be reprogrammed.
"The first thing I did when I got my hands on a programmable computer was to try and make it do something it wasn't supposed to do," said Paul Saffo, director of Institute for the Future, a Silicon Valley think tank.
Saffo said he thinks it makes good business sense for gadget makers to keep an eye on the enhancements, tweaks and hacks that users are making. It's not the executives in the boardroom who figure out how to make a gadget great, Saffo said, but the "fanatics and renegades and people in garages. . . . Hackers create markets."
Roomba's creator, iRobot Corp., is such a believer in letting programmers play with the appliance that it has said it might release tools to facilitate reprogramming.
But many consumer-electronics makers discourage such activity. At the very least, anyone who cracks open the case on a new handheld computer, video game console or digital music player is probably voiding the warranty. At worst, hackers can undermine a company's business.
TiVo supported a "TiVo underground" of hackers as long as users weren't devising ways to bypass the monthly subscription fee. But some users discovered that trick, and TiVo has started to ramp up security on the box, shutting some of the software doors that make modifications possible.
"Companies walk sort of a fine line on this," said Michael Gartenberg, research director at JupiterResearch, a technology analysis firm.
Consumer-electronics giant Sony Corp. generally has not favored unauthorized tinkering on its wares. When one user hacked into a Sony robotic dog and posted directions on the Internet to make the toy dance to music, the company threatened to sue.
Now, the company is waging a quiet battle against attempts to modify its PlayStation Portable, or PSP.
Though PSP sales have lagged behind those of rival Nintendo Co.'s Game Boy, the device has been a smash with hackers, who have reprogrammed it for wireless Web surfing, loaded it with movies from DVD players and turned it into a calculator or drum synthesizer.
But whenever programmers work around the PSP safeguards, Sony releases software that owners must install to play the latest games and that wipes out the homemade functions. The company has updated the software twice, and the PSP came out in North America only three months ago.
"PSP contains robust technology and was designed to run specific applications," Sony said in a statement. "Consumers should be aware that any hacking or homebrew applications may cause damage to the PSP unit, and will void the warranty." The company said the software updates have been made "to prevent this type of damage and protect against various forms of piracy."
Sony has reason to view such hacks as a threat to its bottom line, analysts say.
The same modifications that let PSP users send instant messages also make it possible to download illegal copies of games off the Internet.
Some programmers say that isn't their intent but acknowledge the problem.
"I wish there was a way we could do this without the piracy, but they both come hand in hand," said Sajeeth Cherian, a senior at a university in Ottawa. Cherian has designed free software that helps PSP users put video content, such as recorded TiVo shows, onto the device. The software has been downloaded 650,000 times, he said.
Phillip Torrone, an editor at the techie-oriented Make magazine, said Sony's hard-line stance could be self-defeating. Each attempt to thwart hackers makes them more determined to do their tricks, he said.
Even mainstream users who want to jazz up their devices wind up turning to the Internet for underground help, where they also can learn how to get pirated software and movies.
Torrone, who plays a homebrewed version of chess on his PSP, said he thinks he has a better idea for gadget makers.
"I think the really smart companies should release their products to the alpha geeks for six months and let the alpha geeks play around with them," he said. "It seems to me they'd save a lot of money on R&D, and they'd come out with much more solid products."
Sony threatened to sue a user who made unauthorized modifications to its Aibo robot dog and instructed others how to do so.