Market size: Large (> 10,000,000 people)
Investments required: Medium (< US$5,000,000)
Disabled people are not actually disabled, they're differently abled. Blind people, for instance, are very capable because their others senses are more developed to compensate for their blindness.
In particular, many blind people could be great composers if provided with a specially designed voice recording device that makes it easy for a blind person to record, rewind, play, merge and share musical ideas.