It is more then just being considerate - Design for Accessibility

Many visitors to your web site may have certain physical challenges. Accessibility refers to web designs that remain accessible despite any physical, sensory, and cognitive disabilities, work constraints, or technological barriers. Many web sites are image and media intensive that may not lend itself to adaptive devices such as screen readers, voice browsers, and Braille translators.
Building more accessible content does not mean you have to delete complex and/or rich media sites. Or by offering a text-only based site alternative.

The W3C supports and encourages a accessibility program (www.w3.org/WAI/. This site provides guidelines and standards to build ore accessible web content. Some tips you will find at this site:

• Images and animation – use the alt attribute to describe the function of each visual
• Multimedia – Provide captioning and transcripts of audio ad descriptions of video
• Hypertext links – Use text that makes sense when read out of context.
• Page organization – Use headings, lists, and consistent structure. Use CSS layout and style where possible.
• Scripts, applets, and plug-ins – provide alternative content in case active features are inaccessible
• Tables – make line-by-line reading sensible and summarize
• Validity – check design ad validate code using validators from W3C.
• For physically challenged visitors validate site by using Bobby (www.cast.org/bobby) -recently sold to IBM or similar web-based tools offered by W3C for checking accessibility guidelines.