Reason for 404 Error Pages
A mistyped URL, or a copy-and-paste mistake
Broken or truncated links on web pages or in an email message
Moved or deleted content
Confronted by a 404 page, users may then attempt to manually correct the URL, click the back button, or even navigate away from your site.
To over come this create a customized 404 widget, which will direct the visitor from wrong Url to the closest match Url.
In addition to attempting to correct the URL, the 404 widget also suggests the following, if available:
a link to the parent subdirectory
a sitemap webpage
site search query suggestions and search box
(For more information http://googlewebmastercentral.blogspot.com/2008/08/make-your-404-pages-more-useful.html
)
Implementation Process:
Use the Below mentioned code (Customized One)
<style type="text/css">
/* Widget content container */
#goog-wm { }
/* Heading for "Closest match"
#goog-wm h3.closest-match { }
/* "Closest match" link
#goog-wm h3.closest-match a { }
/* Heading for "Other things" */
#goog-wm h3.other-things { }
/* "Other things" list item */
#goog-wm ul li { }
(http://www.google.com/support/webmasters/bin/answer.py?answer=100044&hl=en )