Accessibility
Contrary to what many designers/developers may have you believe, accessibility is not just about producing Web sites that validate. Accessibility is ultimately about the art of universal design that requires calculated planning and careful attention to detail. Accessible applications must serve the most diverse spectrum of possibilities; therefore, accessibility does not imply that benefactors are limited to people with physical disabilities. Ideally any user, utilizing any standard device, should be able to use Web applications. The list includes cell phones, PDAs gaming consoles, digital television, screen readers among other assistive and emerging browser devices.
The value of accessible design lies within its inherent diversification that allows users from any culture and environment to access and digest your information.