It's nice to think that your pages are usable by everyone but are they?
Accessibility standards are very much developing and the subject of debate. The W3C validation checks also comment on accessibility in the form of ALT tags for images. These are read out by screen readers for those with sight problems. In addition to that you should choose clear fonts and colours which make reading easy.
Put yourself in the place of someone who is blind or deaf or partially so. Can the page be resized well (try Control +)? Could you build in a JavaScript function to change the base font size without the user having to resize the page? Are sounds crucial to using the page or have you provided text alternatives?
How about those who would struggle to use a mouse. Can you navigate your site without a mouse (maybe using keyboard shortcuts)? If not you may need to sacrifice some fancy looks to make it more friendly.
When you create a form make sure you use labels for the fields so that screen readers can associate the field descriptions with the fields themselves.
Start thinking now about making your sites as open to everyone as possible. Don't wait until someone takes legal action against you for not doing it!
