Despite this year's health care system overhaul, health care costs -- particularly at hospitals and primary care providers -- are soaring. As the elderly population also grows and demands less expensive, out-of-hospital care, the industry is expected to expand by an average of 4.9 percent through 2014, according to IBISWorld.

This industry, which was also on Inc.'s 2009 list, has been strong for years and yet retains a low barrier to entry.

Subsectors of the field include physical therapy and ambulatory delivery of new technologies. Nonmedical home care hiring is expected to grow more than 50 percent before 2018.

By the numbers:

Expected annual revenue expansion of "home care providers" through 2014, according to IBISWorld: 4.9 percent

Ranking of "Services for the elderly and persons with disabilities" in's "fastest-growing industries that are hospitable to small businesses": 6

Estimated number of Americans age 65 or older as of June 2009, according to IBISWorld: 39 million

Year-over-year growth rate, according to 8 percent

Sales growth for "home health care services," according to Sageworks: 11.38 percent