iPad/iPhone app for people with disabilities

I am developing an eBook reader app for the iPad. This app also contains facilities like audio playing, video playing, making notes, etc.

Now I want to add some features so that this app can be of help to the people who are visually impaired (blind) or hearing impaired (deaf). I know that there is a framework called UIAccessibility in iPad for this specific purpose, but I could not find suitable sample code from apple or from any other developer regarding this issue.

Right now I'm a bit confused regarding how to proceed forward. Can anyone suggest me a few ways, methods or sample code for doing this so that I can proceed forward with my idea?

There are excellent WWDC session videos (both 2009 and 2010) on using the UIAccessibility API. Available through Apple's iOS developer portal.