What, exactly, is required of a nonprofit when it comes to the ADA anyway?

I just came across this, which seems like a great "intro" to the issues of equal access.

Title III Technical Assistance Manual http://www.ada.gov/taman3.html (1993) and Supplement http://www.ada.gov/taman3up.html An 83-page manual that explains in lay terms what businesses and non-profit agencies must do to ensure access to their goods, services, and facilities. Many examples are provided for practical guidance. (Spanish edition available from the ADA Information Line.)