Pet rocks. Cabbage Patch Kids. The Rubik's Cube. The marketplace, like the Billboard charts, is full of one-hit wonders—products that come out of nowhere, capture the national imagination, then just as quickly turn into punch lines and trivia answers.

But what about the entrepreneurs behind these creations? What do they do after the novelty of their novelty products wears off?

We decided to find out. We tracked down four people who introduced some of the most popular fad items of the past few decades to find out how they handled their sudden prosperity—and rapid exit from the limelight. Some were relaxing and enjoying their spoils. Others were trying to capture lightning in a bottle one more time.

Here are their stories.

Stuck on Poetry

A sneeze helped make Dave Kapell the spiritual bard of the refrigerator door.

Dave Kapell, creator of Magnetic Poetry. Eli Kapell

Back in 1993, the Minneapolis native was an aspiring musician who liked to cut up his diaries and rearrange the words to create song lyrics. But he was prone to allergies and, with the pollen count soaring one day, he sneezed and scattered an almost-finished song. An idea was born: Why not stick magnets on the bits of paper and affix them to a cookie sheet to keep them in place?

The contraption stayed in Mr. Kapell's room for a few months until he threw a house party and needed the cookie sheet for baking. The word magnets went up on the refrigerator—and throughout the night, Mr. Kapell's friends kept stealing back to the kitchen to scramble the lyrics. The next day, he got a half-dozen orders for the magnet kits.

"Within a month of the party, it was like I was selling drugs out of my house," says Mr. Kapell, who is 48. "It went viral before viral was a term."

Soon he was making more from his Magnetic Poetry kits than from his $8-an-hour job in data entry, which he promptly quit.

Friends in retail said he might not have a lot of time to exploit his big opportunity. So, he pored over books on start-ups and worked 90-hour weeks to build the brand. By 1995, Mr. Kapell and a partner had set up a company, U.S. Magnetix, to produce custom magnets in China. To get prime placement for his kits, he prowled gift-shop conferences and craft fairs, where he found himself treated like the rock god he once dreamed of becoming.

"I knew that I had hit an atypical home run," he says. "At trade shows, everyone would say, 'Everyone wants to be you.' "

Magnetic Poetry

Mr. Kapell wooed big chain bookstores to get prime locations in their checkout aisles but didn't ignore mom-and-pop stores. He says his close relationship with that close-knit segment has kept copycat products off the shelves.

To encourage repeat customers, Mr. Kapell started brainstorming new ideas, such as packs with oversize words for kids, foreign-language versions and ones with themes such as geeks, Christmas and bike lovers. "I don't necessarily like the business side of this," he says. "Dotting the i's and crossing the t's is not what I'm best at. But I like coming up with new products."

That urge, however, led to some missteps. In the late 1990s, Mr. Kapell tried to develop a software version of the poetry kits, as well as a game. Both led to steep losses. Another venture, Poetry Stones—a kit that let crafters frame their messages in quick-set cement—was initially successful but tailed off quickly.

Fad Blasts from the Past

These days, the recession has hurt sales, as have the tenuous fortunes of his two biggest customers, Borders and Barnes & Noble. Mr. Kapell says he is looking to broaden distribution and is considering a Magnetic Poetry app for the iPhone and iPad. He's also making changes in his company's online store to make direct sales easier.

In general, though, he says he's content to issue a half-dozen or more variations on the original kit each year. A zombie-themed kit is popular, he says, and erotic-word versions are perennial favorites. A recent golf-lovers' kit, on the other hand, was a dud.

Mr. Kapell wouldn't respond to questions about exactly how much he's made from the kits. But, he says, even with the current slowdown, profits from Magnetic Poetry have allowed him to play gigs more than he ever could as a struggling musician. He frequently plays ukulele with a local burlesque troupe and drags along a vintage stand-up bass on camping trips with friends. His house is decked out with a grand piano and a 70-piece ukulele collection.

And he thinks the business has staying power. "It's not a pet rock," Mr. Kapell says. "It actually has utility. We get letters from people every day who are fans."

It's All In the Wrist

Robert Croak had built a nice business marketing novelty products, but he wanted something that could lift his company into the big leagues.

Robert Croak, creator of Silly Bandz. Bloomberg News

On a trip to a supplier in China in 2007, the Toledo, Ohio, businessman came across a product that seemed to fit the bill: a thin, brightly colored silicone band shaped like an animal. It was designed for office workers, but Mr. Croak thought the concept had much greater potential as a mass-market bracelet for children. So, he began working on his own variation on the theme—Silly Bandz.

The 47-year-old Mr. Croak says the product sold in dribs and drabs at first. But he says he knew he had a hit on his hands when a store called in late 2007 and ordered 500 packs. "Within 10 days or two weeks, the phone started ringing off the hook," he says.

Marketed in theme packs for under $5, the bracelets became a huge schoolyard fad and eventually sold in the millions. To stoke interest, Mr. Croak and his team at BCP Imports LLC kept releasing new themes, from animals to popular cartoon characters to corporate logos.

Early on, however, BCP couldn't keep up with demand—or answer all the calls coming in from frantic retailers. An eight-line phone system was hastily upgraded to 48 lines. The company's lone server proved inadequate after a CBS News segment on Silly Bandz led to 11 million hits on the product website; the company now has three servers.

"It was difficult," Mr. Croak says. "We had to figure out how to handle all the growth. But I always tell people, if you hear me complain, slap me."

Silly Bandz Associated Press

As the economy crumbled in 2008, sales of Silly Bandz kept growing. At one point, the company was so overwhelmed with shipping orders that Mr. Croak sent out a plea for night-shift workers on Facebook. A few hours later, a line of applicants snaked around the block. "We had to lock the door because we had so many people show up," Mr. Croak says.

The hiccups in logistics allowed copycat manufacturers to get a foothold. "I don't think the knockoffs would have really gained any ground had the retailers not been in dire need of inventory," Mr. Croak says, adding that BCP is vigorous in protecting its copyrights.

Although demand is rising for Silly Bandz abroad, the product has already peaked in the U.S. Mr. Croak says he was planning for a slowdown a year ago, and so BCP has introduced a range of new items: the Slap Watch, which has an oversized, brightly colored silicone wristband; Rad Bandz, thick rubber bracelets imprinted with stylized words such as "Drama" and "Epic Fail"; and RadRingz, a colorful, two-finger ring—Mr. Croak calls it "half a brass knuckle"—with removable faceplates.

"The goal is to become a lifestyle brand of fun, innovative new fashion products that kids can buy for under $20," he says.

Mr. Croak won't disclose just how much his breakout product brings in, except to say that the profits are in the "millions per year," and he's probably set for life. What's more, "Silly Bandz gives me the capability to dream big and not be stifled by lack of resources."

He says he realizes he may not ever have a hit like Silly Bandz again. Yet he still gets a kick when he sees his products in a store, and wants to keep the momentum going. "To me, it's about the chase and conquer," he says.

Million-Dollar Baby

Michael Lerner's journey to entrepreneurial stardom began with a white-knuckled ride down Storrow Drive in Boston.

Michael Lerner, who introduced the Baby on Board sign. The Lerner Family

Mr. Lerner had agreed to drive his 18-month-old nephew home after a Sunday gathering at his parents' house in 1984. Childless himself, he soon realized he had failed to account for the hell-bent traffic on Storrow, a notoriously busy expressway along the Charles River. "People were tailgating me and cutting me off," he says. "For the first time, I felt like a parent feels when they have a kid in the car."

Soon after that nerve-wracking trip, a friend called with a tip for Mr. Lerner, who was looking to move out of the executive-search business and into consumer products. Two sisters wanted to sell a safety sign for car windows; they had seen it in Europe but didn't know how to market it.

It was kismet. Mr. Lerner struck a licensing deal for what would become the Baby on Board sign. "I believe things happen for a reason," says Mr. Lerner, now 59.

Using his contacts in the retail industry, he started pitching to big department stores. The first month, his company, Safety 1st, sold 10,000 signs. Within nine months, it was selling 500,000 a month. "It ramped up real fast," he says. "Around Boston, I couldn't go down the street on a particular day without seeing one."

By 1985, the first knockoffs started appearing, but Mr. Lerner had developed strong relationships with his retailers and was able to protect his shelf space. Sales really didn't start to dip until the parodies came, like "Mother-in-law in Trunk" and "Baby, I'm bored."

"They weren't funny at the time to me," Mr. Lerner says. "But they really were a little funny."

Baby on Board sign Image Source/Getty Images

By the start of 1986, the fad was fading. Safety 1st had already introduced other products, including a Tot Spotter decal to help firefighters quickly locate bedrooms where children might be sleeping. But Mr. Lerner saw a bigger opportunity in child-safety products for the home.

At the time, gadgets like outlet covers and drawer locks were consigned to odd corners of hardware stores and other hard-to-find spots. Starting in 1987, Mr. Lerner began transforming the sales niche with more colorful packaging, new designs and lower prices. "We had a really good, innovative team," Mr. Lerner says. "We were very nimble."

Safety 1st also capitalized on the rise of the big-box stores, developing strong bonds with companies such as Toys 'R' Us, Wal-Mart and Kmart. Between 1989 and 1996, sales grew to $105.8 million from $7.7 million, according to regulatory filings. By 1999, with sales at $158 million, the company began fielding buyout offers—and ultimately agreed to be acquired by Canadian company Dorel Industries Inc. in June 2000.

It was then that Mr. Lerner got his big payday. During the Baby on Board boom times, he says, he reinvested the profits from the product to fund the growth of Safety 1st, so didn't see any real money until the sale—$38 million, according to regulatory filings. (He also sold some shares during Safety 1st's initial public offering.)

After the sale, Mr. Lerner spent much of the next decade traveling, spending time with family and playing golf—which led him to his current venture. He damaged some ligaments in his thumb, and after surgery the digit would get inflamed after workouts or golf games. Then he started using a therapeutic band that helped eliminate the inflammation and the need to routinely ice the thumb.

The band worked so well that he decided to sell his own version of it, through a Boston-area start-up called True Power. The company, which has testimonials from several New England Patriots, claims the bands use negative ions to speed oxygen delivery in the blood, which in turn hastens recovery from injury and fatigue.

"I know there's some skepticism about the product with some people, but it really does work," Mr. Lerner says, adding, "It's easy to sell a product, but it's more meaningful to sell a product that adds value."

Big Hair Day

May 2007 was not shaping up as a banner month for Kelly Fitzpatrick-Bennett. Her career as a mortgage broker was on the rocks as the California real-estate market imploded, and her first husband had just filed for divorce. "I was sitting in my room crying, which is unusual because I'm so optimistic," she says.

Big Happie Hair's Chief Executive Optimist Kelly Fitzpatrick-Bennett, inventor of the Bumpit. Jillian Anaya

An episode of "The Big Idea with Donny Deutsch" popped up on the television, and Ms. Fitzpatrick-Bennett was captivated. Mr. Deutsch talked about finding something you love to do and using that to come up with a money-making venture. She watched the program three nights in a row and read through a list of recommended books on start-ups.

Ms. Fitzpatrick-Bennett, now 48, knew one thing she loved: styling hair. She had run a small salon from 1994 to 2001, and her customers invariably wanted their hair to appear fuller. A good stylist can bump up hair to give it more volume, but that wasn't an everyday option for most of her clients. At the time, she wondered if a hair insert could solve the problem, but never followed it up.

Now she pursued the solution with a vengeance, crafting prototypes out of popsicle sticks, Velcro and whatever else came to hand. She used her college-age daughter, Katherine, as a half-willing test subject.

"Growing up poor, I was a chick MacGyver," she says. "If you didn't have something, you make something."

The Bumpit. Big Happie Hair

She enlisted a design engineer to help smooth out flaws in her model, a crescent-shaped insert that propped up teased-back hair and gave it extra loft. Ms. Fitzpatrick-Bennett dubbed it the Bumpit, and a friend with a plastic-injection-molding business began limited production of the device.

She also set up a website and an office in Fresno, Calif., for her company, which she called Big Happie Hair. Her title: chief executive optimist.

Ms. Fitzpatrick-Bennett started going to hair-product shows, and the response was immediate and overwhelming. "Our booth would be mobbed the entire day," she says.

Her friend's manufacturing business could only provide 200 units a week, not nearly enough to meet demand, so she found another supplier in San Francisco. With more inventory, the company was ready for more exposure, but Ms. Fitzpatrick-Bennett didn't want to pay for a professionally produced commercial. So she made a homemade one featuring her daughter and some of her sorority sisters, who were paid $50 each plus dinner from Panda Express.

When the ad showed up on MTV, orders came pouring in. Soon celebrities were touting the Bumpit, including Carrie Underwood, American Idol participants and Miss USA contestants, Ms. Fitzpatrick-Bennett says.

Big Happie Hair's 20-person operation found it difficult to keep up with orders, and Ms. Fitzpatrick-Bennett realized she needed a partner with better distribution. In 2009, she struck a deal with Allstar Products Group, a company that licenses such products as the Snuggie blanket, promoting them under its "As Seen on TV" brand.

Last year, though, sales started to slip, and parodies started popping up on TV. Ms. Fitzpatrick-Bennett says she doesn't mind the backlash. "As long as people are talking about it, it's good," she says. "Most late-night shows did spoofs, and we loved it."

At its peak, the Bumpit sold at a clip of a million units a month. Ms. Fitzpatrick-Bennett's current business plan calls for sales of about 20,000 a month. "I was pretty realistic in knowing it would only have a year of good life and then it would just sit and stop," Ms. Fitzpatrick-Bennett says.

With more time on her hands, Ms. Fitzpatrick-Bennett has begun to look for bargains in rental properties and foreclosed homes. She won't say just how much she's taken in from her signature product, but "she could retire now," she says.

Meanwhile, the money has allowed her to buy a large Tudor mansion with four guest houses, and she drives a new Honda CRV instead of a used car. (Some of her newfound good times aren't tied to money, of course: She remarried in December.)

A follow-up product to the Bumpit hasn't fared as well as the original, but "I would love to continue inventing other products," Ms. Fitzpatrick-Bennett says. "If I had a dollar for everyone who said no, I'd be richer than I already am. When someone says no, there's always another avenue."