Ian Lurie offers a step-by-step guide to creating a "great" 404 not found page, including how to build it (via HTML or a Web page editor), upload it and get your server to point to it--whether via Microsoft's Internet Information Server (IIS) or the open-source Apache server.
He also lists the three components a quality 404 page must have, including a clear statement that the visitor is in the wrong place, advice to help get them back on track (via either links, a search box, etc.), and an option to contact the Webmaster.
What a 404 error page shouldn't do is automatically redirect a user to the homepage, a Flash page or tedious registration form, or worse--another Web site!
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