(FORTUNE Small Business) – When he went to lunch with a friend who has cerebral palsy, Patrick Hughes, 36, was surprised to learn that there were 25 businesses in her neighborhood in Evanston, Ill., that she couldn't patronize. Most were small establishments. Despite the passage of the Americans With Disabilities Act in 1990, many had doors that were hard to open or too narrow for her wheelchair--or had steps that blocked her. Hughes, who was head of a Chicago-based nonprofit group called Natural Ties, which aimed to bring citizens with disabilities into the mainstream, started to seek solutions that would be practical for small businesses.

Realizing that adding power doors or ramps could be prohibitively costly, Hughes came up with a cheaper fix: a giant doorbell called the BigBell, which could be installed at wheelchair height and operated by either hand or head contact. It alerts employees inside a business that a customer needs help getting in, and allows the business to offer the access that ADA requires. Hughes set up a Chicago-based business, Inclusion Solutions, which sells both a wireless doorbell system for $119 and a long-range version for $199. Noticing that smaller firms faced an increasing number of ADA suits, he marketed the gadgets to them through his website.

Terry Smith, CEO of Tumbleweeds, a Louisville-based chain of 55 restaurants, says that the BigBell helps customer relations. "At the opening of our newest restaurant, one guest remarked on the bell and said that it sent a very positive message," he said.

The BigBell was also a hit during last year's elections. "More than 65% of polling places in America are inaccessible, preventing about five million voters from exercising their civil rights," says Hughes. So he sold Inclusion Solutions' Voting Access Kit, which includes a BigBell and signs saying that a polling place is accessible, to more than 1,000 local and state election authorities. The extra sales pushed his four-year-old firm into the black last year on sales of nearly $1 million.

What's next? A tool, still in development, that will allow hearing-aid wearers to use the speakers at drive-through restaurants. --ELLYN SPRAGINS