Supporting Cast Creating accessories for a hot-selling product line can be the path to quick riches, but it's also a very risky business.

Four years ago, Jason Entner was first in line to snap up Apple Computer's original iPod. He loved its size and sound, and it became his traveling companion at trade shows, where he promoted his fledgling home-accessories design firm. But Entner felt something was missing. His iPod needed a case, and there wasn't anything on the market. So he started designing his own cases. "It was something to house my iPod, as well as [an] extremely deficient [niche] in the market," says Entner, 33.

Today, Lifepod, founded in 2002, designs and manufactures funky accessories for iPods, from cases and "cooler bags" to wallets and iPod-friendly laptop cases. Lifepod's products are sold at Urban Outfitters, specialty stores and college bookstores. It's been an amazing ride for Entner, who works alongside Lifepod's four full-time employees in the company's New York City office. Apple Computer has sold about 42 million iPods to date, which in turn powered Lifepod's 2005 sales to more than $1 million. Three years ago, "nobody knew what an iPod was, so why would anybody buy a case for one?" he says. "This past Christmas, the [iPod] was one of the [must-have] gifts."

The trend toward personalization is a driving force behind today's accessories market. "People want to buy a product because everyone else is buying [it], but they want to differentiate it from everyone else's," says Arvind Malhotra, associate professor of entrepreneurship at the University of North Carolina, Chapel Hill's Kenan-Flagler School of Business. "As an entrepreneurial business, there's a huge opportunity if you can offer any sort of customization."