The latest edition of Exploit Interactive is devoted to accessibility and internationalisation (if I can spell it!). There's a good article about the W3C Web Accessibility Initiative which talks about their purpose and goals and describes some of their achievements (such as the Web Content Accessibility Guidelines)

As the Web rapidly displaces existing media, there is an increasing social expectation for its accessibility, and also a growing trend to require accessibility. This, combined with the realization of the benefits that a Design for All approach can bring to the Web at large (for instance, to mobile phone users with limited display screens), led the W3C to take on a leadership role and launch the Web Accessibility Initiative (WAI) program in 1997.