To paraphrase Supreme Court Justice Potter Stewart’s famous remarks about obscenity, the concept of the "gadget" is not easy to define—but we know a gadget when we see it. They capture our imaginations like little else. We become compulsively attached. The best gadgets fulfill basic needs we're hard-pressed to describe, and because of that possess a magical ability to conjure money. They become talismans for economic vitality, as the gadgets in this gallery show. While the "gadget" predates the invention of electronics, we stuck to devices that one way or another make use of electricity, in keeping with the 21st-century sense of the word. We also decided that for this list, a gadget was something a person had to be able to hold and more or less use with one hand, which ruled out laptops, for example. We picked gadgets that tipped toward the "gizmo" side of the continuum. The gadgets we chose weren't just popular. They didn't just make their inventors or manufacturers a lot of money. These diminutive devices cracked open the earth, shoving tectonic plates east and west to build new mountains of economic activity. They demonstrate the profound capacity of the most unassuming bits of metal, glass and plastic to transmute the basic elements of labor and commerce into new sources of gold. Above: Motorola DynaTAC You could be forgiven if in the early 1990s you didn't take investment advice from Zack Morris of Saved by the Bell. But his conspicuously incessant yapping into his Motorola DynaTAC-style mobile phone put Zack in the vanguard of a fundamental change in the way human beings interact—a change that minted a trillion-dollar industry. The DynaTAC went on sale in 1984 after the FCC approved the 2.5-pound device as the world's first consumer-grade cell phone. At a cost of nearly $4,000 for the handset alone, Zack's DynaTAC signified him as the preppy, privileged rich kid. But his ugly brick turned out to be simply the first domino in a technological cascade that has spread across the world with amazing speed. Just 20 years post-Zack, a new World Bank study finds that 75 percent of the world's population has access to mobile phones, including much of the developing world. Photo: mikek/Flickr

Regency TR-1 Transistor Radio At $49.95, the Regency TR-1 effectively launched the category of the portable, consumer-grade electronic communications gadget when it hit the market in 1954. Six years earlier, researchers at Bell Labs had hailed their new invention, the transistor, for its potential to transform communications technology, which until then was weighed down by cumbersome vacuum tubes. Texas Instruments won the race to turn Bell Labs' invention into relatively affordable, assembly line-ready gadgets with the Regency TR-1. Other companies quickly caught up, and transistor radios sold by the billions through the 1970s, as they morphed into the boom box, the Walkman and the iPod. That’s hundreds of billions of dollars right there. But the economic impact of the transistor radio extended beyond the electronics industry itself. When music became handheld, music changed. Even with the advent of modern stereo systems in the first half of the 20th century, listening to music was still a shared experience. When you walked down the street holding the Regency TR-1 next to your ear in the mid-1950s, just as rock 'n' roll was becoming a major cultural force, music took a huge step away from performance toward becoming private. In the ensuing years, the modern pop music industry grew around an ever-increasing atomization of taste made possible by the portability and personalization of music—a concept that by the smartphone era would evolve to embrace all forms of media. Photo: Gregory F. Maxwell/Wikimedia

Zenith Space Command Television was a different experience before the remote. Witness the early seasons of “Mad Men,” when the Draper children huddle close to the fuzzy screen and its adjacent knobs, versus more recent episodes, when Betty Draper sits on the couch with her Bugles and her "clicker." The first such device that really worked came out in 1956, at a time when companies still gave gadgets totally awesome names. The Zenith Space Command was indeed wireless, though in an endearingly old-timey way. Not electronic in itself, the Space Command used tiny hammers to send out high-frequency pings inaudible to the human ear but which the TV "heard" as a command to change the channel. The remote makes channel-surfing possible, and the modern cable industry is a function of channel-surfing. Would cable exist if you had to get up to change the channel 600 times? The modern infrared remote hit the market in the early '80s as cable went from novelty to just another utility bill in American household budgets. Photo: Todd Ehlers/Flickr

Atari 2600 Joystick Console video-gaming may have started with Pong, but didn't really deliver that addictive rush until the joystick. The handheld controller made interacting with microprocessors a visceral experience, removing the layers of abstraction between you and your machine. And what experience was more visceral than grabbing an Atari 2600 joystick and mashing its big red button? Kids in the early 1980s would bob and weave with their joysticks as if doing so could have affected the action on the screen, the way a Wii controller would do decades later. The 2600's joystick put you physically into your machine years before haptic feedback, delivering a primal form of satisfaction that fuels the billion-dollar demand for the console gaming experience to the present day. Photo: Evan-Amos/Wikimedia

Handheld Barcode Scanner Barcodes provide the information infrastructure of the modern consumer economy. Granted you don't need a handheld scanner to read a barcode—the scanner can live under glass, as at the grocery store. But wireless handheld scanners liberate barcodes from the physical constraints of the factory or the big-box store. They make possible a ubiquitous data layer for global commerce. They make FedEx, UPS, Walmart and Amazon possible—in fact, the handheld scanner enables the entire 21st-century supply chain. Thankfully, they also make it possible to get through the IKEA checkout line without having to lift your Malm bed frame onto the counter. Photo: david roessli/Flickr

The Land Camera For 60 years, the Polaroid Corporation sold instant gratification in a box. Scientist Edwin Land in 1948 put on sale in Boston a few dozen of his Land Cameras, which took advantage of his research into the polarization of light to compress the time-consuming process of developing and printing photos from film or plates into a one-minute wait. Thanks to Land, the concept of near-instant visual memory became a reality. Polaroid itself made billions of dollars annually selling its cameras and film, falling into bankruptcy only when the company failed to make the jump to digital photography, which fulfilled the promise of the Polaroid with exponentially greater resolution and speed. But Land in a sense deserves credit for digital photography, as well: Polaroid cameras created the expectation, and as such the market, for a technology capable of creating an immediate record of our most recent history. Photo: Morven/Wikimedia

iPod/iPhone/iPad So obvious as to almost not bother mentioning. Each one of these gadgets has woven a new economy around itself the way the monolith in 2001 turned apes into tool-wielding humans. For a decade, the iPod has dominated the market for digital music players and in turn effectively created the market for digital music. Prior to the iPod, Napster junkies were still burning their MP3s to CDs. The iPod made those MP3s portable, and Apple with the companion iTunes store created the first viable legal marketplace for music sold without coming into contact with a physical medium. The iPhone generates not just billions in hardware sales, but birthed the whole app industry. When the iPad was revealed, the underwhelmed consensus was, “It’s a giant iPhone.” Yet the new form factor created a set of conditions that a very great number of people found they lusted after. Instead of inventing a new ecosystem the way the iPhone did with the app store, the iPad moved the entire PC industry forward, and left competitors in a vacuum that they needed to fill with touchscreen tablets of their own. Apple in the meantime sucked up profits. Photo: redjar/Flickr