It happens to the best of us - 404 errors. Whether it's because of a mistyped URL, broken or truncated link within an email or because of content that has been moved, end-users often see these error pages - but there are ways to help visitors get the most from this experience.
Google has added a section called "Enhance 404 pages" to its Webmaster Tools service. The embeddable widget can be included in a custom 404 page to help visitors find what they are looking for by providing suggestions based on the incorrect URL. For example, say a user visits a link which for whatever reason gets cut off and a 404 page appears. Add the Custom 404 Error Page widget however and the visitor would see the following:
Google will not only attempt to correct the URL but suggest a link to the parent subdirectory, a sitemap webpage and provide a site search query suggestion and search box. If you're interested, simply sign into Webmaster Tools and generate a JavaScript snippet which can be copy and pasted into your existing 404 page code.