Accessibility means planning and developing applications in a way in which everyone will be able to use them, including blind, persons with low vision, with motion disorders, etc.
Screen Reader Support
The first step in testing screen reader support is installing one and being able to use it to check what users will see when using your application.
Mac OS X VoiceOver
The screen reader for the vast majority of users in Mac OS X is VoiceOver which comes pre-installed in Mac OS X. To activate it go to Settings->Universal Access and turn VoiceOver on. It couldnt be any simpler. Using it is also mostly easy and intuitive.
Orca for Linux
Orca is currently the most popular screen reader in Linux for both GNOME and KDE. See: http://en.wikipedia.org/wiki/Orca_(assistive_technology)
Accessibility Inspector Tools
Accessibility inspectors can help a lot at checking if the application is giving correct information.
Mac OS X
In /Developer/Applications/Utilities/Accessibility Tools/ there is an Accessibility Inspector which will be very useful when developing in this platform.
Search Google for:
site:developer.apple.com carbon accessibility
Microsoft Active Accessibility
AT-SPI for Linux
|TLazAccessibleObject||Qt||Mac OS X||MSAA||AT-SPI||Comments|
|Description||QAccessibleWidget::setDescription||AXRoleDescription and AXDescription||?||?||-|
|Value||QAccessibleWidget::setValue||AXTitle, AXValue||Value, Name, State||?||-|