Vendors have begun to include the accessibility features of their browsers on their websites. It is useful to alert your users to this information and indicate to them how they can use this information to customise their browsers. This customisation includes controlling fonts, colour, graphics and animations. Providing this information will help users to enhance their web access to meet their particular needs. This site provides an example of how this information can be provided. See Accessibility Information Page.
Microsoft has this information about Microsoft products, including Internet Explorer, on their site at http://www.microsoft.com/enable/products/docs/default.aspx
Netscape also provides information on using their browser on their site at http://browsers.netscape.com/browsers/using/main.tmpl
Mozilla provides customising information at http://www.mozilla.org/access/users
Safari, a browser for Macintosh, has similar information at http://www.apple.com/macosx/features/safari/