[peterb]

+1. Accessibility is in huge demand right now and setting up a consultancy could be very interesting for you as you get to see issues and patterns across companies. Most, if not all, Fortune 500 companies are interested accessibility.

[SpaceL10n]

+1 again but it's not just the Fortune 500. My employer (15 employees) hired a blind technology consultant when we were designing a kiosk for a major US Airport. We invited a blind user from a local non-profit advocacy group to come try our product and talk to us about our choices of tactile controls, audio feedback cues, etc... From that one engagement, we received immensely valuable insight into the average blind user's fears and expectations when it comes to dealing with kiosks in public. There's a definite need for expertise in this space.