Screen Refresh
Be aware that some persons with a physical or visual disability may take longer to both read and navigate your site. Therefore pages that use an auto update or auto refresh may be unsettling at best and totally inaccessible at worst. Try letting the user control the updating or refreshing.
Example
Page that automatically refreshes
Links
Screen Refresh Guidelines
and Explanations
(http://www.w3.org/WAI/wcag-curric/chk8-0.htm)
