Yes, the Internet Is Littered With Dead Web Sites. In general it’s a good idea to keep all links on your site live so that bookmarks, external links, and search engine databases can find the content or be redirected to newer information. But what to do if the entire site is going to be adandoned?
Or you could leave it up for archival purposes. This is probably the best solution as there is a long-term issue with information that may have historic information disappearing. In “olden times” we could refer to people’s letters, diaries, and books to see what people in the past thought. With ephemeral electronic records much of what we rely on to decode the past will be gone. Archiving your site is less of an issue if the Internet Archive has already cached a copy of your site. In that case they are effectively hosting the archive of the site for you.
If maintaining the site as an archive is not an option, you may consider pointing all pages on the deceased site to one page that explains what happened and offers the reader suggestions on where to go for current information. If you have a site you can’t afford to host anymore, you could still maintain the domain for a few dollars a year and point the entire domain to a free/cheap page hosted elsewhere that explains the fate of the site.
If a site it to remain live after it is outdated, it is important to identify the new purpose of the site (historic archive) and to ensure that people know that your information may no longer be relevant. A “last updated” reference is particularly useful in this case.
(Thanks to Gerard Dolan for the link)