1. Real estate: Feather upscale nests. The real-estate market has gone through the roof in the past few years and while some pundits nervously point to air leaking out of the bubble, houses aren't bought and sold in a New York minute, like stock. So even if the torrid pace slows, many markets remain hot. More to the point, the top end of the market has been largely immune to economic ups and downs while the how-low-can-you-go mortgage rates motivated thousands of homeowners to leverage their equity and trade up. That translates into opportunities for high-quality services for child care, household help, interior and landscape design or maintenance, and home alarms or security.Carrie Zeier figured it out after moving eight times in six years because of husband Eric Zeier's football career. (Eric Zeier, a University of Georgia star, was a quarterback for several NFL teams.)"When Eric was in the NFL, I always had a hard time finding staff," says Zeier, a mother of two. "I would talk with the other wives and realized they were having the same problem. I didn't know how to find someone I could trust." In 2001, Zeier took over a domestic placement business in Atlanta and launched Estate Domestics. She supplied celebrity and affluent homeowners from Beverly Hills to Europe with housekeepers, nannies, bodyguards and certified nurse assistants. Within four years, Zeier got a great offer and sold her company for a profit.Also, consider that home service companies require support systems, like recruiters, accountants, marketers, product suppliers and private investigators. Estate Domestics, for example, runs a full background check on every applicant.

2. Pets: Make hay with fur or fins. Nowadays, 63% of U.S. households own a pet, which translates into more than 69 million homes, according to the American Pet Products Manufacturers Association. Americans are spending a staggering $36 billion a year on pet supplies and care. And they're treating pets like one of the family. This "humanization of pets" suggests many business ideas, including (yes, really) luxury pet resorts and spas, grooming services, gourmet pet food and delivery services, pet sitting, day care and walking services. Pet toy design and manufacture is also blossoming. Of course, there's been a parallel rise in products that handle pet dirt and odors as well as all that fur and hair that collects in your house.To tap into the market, imagine human or child-care needs that can migrate. Pet obesity, for instance, is a growing problem. Health and life insurance policies for pets are likewise skyrocketing.

3. Senior care: Bet on boomers. As you've surely heard, Americans are living longer and enjoying active retirements. During the 1990s, the population of seniors over age 85 increased by a dramatic 37%, compared to only a 13% rise in the overall population, according to the U.S. Census. So senior-care businesses are burgeoning — regardless of whether they provide products or services, and whether they cater to in-home or facility use. Bigger opportunities are yet to come.In 2011, the first wave of 80 million baby boomers will turn 65. By 2030, one in every five people is likely to be 65 or older. There are dozens of businesses that can serve this dominant generation that intends to stay forever young. Try investigating cosmetic maintenance or makeover services, from dentistry and plastic surgery to chiropractics and physical therapy, massage and spa services, skin-care services and products, and makeup and fashion, as well as senior educational, recreational or travel agencies. Also, consider long-term care insurance, medical supply, home design products or services that help the aging and disabled, and in-home food and delivery services.Home Instead Senior Care, for example, provides non-medical home services, such as meal preparation, medication reminders, light housekeeping, transportation or errands and shopping for roughly $12 to $20 per hour. "Population projections were the fuel that helped found Home Instead Senior Care in 1994," says owner Paul Hogan, based in Omaha, Neb. "And they're the primary reason why our company and other eldercare services are growing so rapidly."A year after launch, Hogan franchised the concept and, today, there are 600 independently owned and operated franchises in the United States, Canada, Japan, Portugal, Australia and Ireland.

4. Technology: Profit on the cutting edge. Technology-based businesses in information and life sciences probably now provide the best opportunities for people in startups. The biotech industry is particularly hot. "We're on the brink of major breakthroughs in the next 10 years of developing diagnostics and therapies that will cure major diseases like cancer and autoimmune diseases such as diabetes and MS," says Marcia Mellitz at the Center for Emerging Technologies, a nonprofit incubator in St. Louis.To get ahead of this curve, consider training and staffing agencies that specialize in life sciences technicians or bioinformatics, as well as management, sales and marketing services for science-based businesses, legal and paralegal services and bioengineering products, such as medical devices, robotic instruments and software.

5. Organic foods: Go for green. Escalating fears about the safety of the food chain because of mad cow and other outbreaks are changing public perceptions. Increasingly, consumers are paying a premium to buy organic or local products.Larry Bennett, director of the entrepreneurship center at Johnson and Wales, the hospitality business school in Providence, R.I., often advises startups. "The recent explosion of ideas has revolved around organic foods and beverages," he says. One group plans to grow and distribute exotic herbs for upscale restaurants and caterers along the East Coast. Another, an Italian organic vineyard, is looking to import wine.The trend will likely continue to grow because of super-sized Americans. Millions of people are desperately trying to lose weight and get healthy. Calorie- and health-conscious foods as well as diet and fitness services are going gangbusters. Consumer spending in Europe and the U.S. on diet-related food and drink is expected to grow to over $100 billion by 2008, up from $87 billion in 2003, according to a market report from Datamonitor.Businesses poised for takeoff include health-food products or bricks-and-click retail shops, carryout food services, meal preparation and delivery services, exercise products or instruction.