I read an article on A List Apart about creating “A More Useful 404”. I also think that it’s important to give better feedback to the visitor who ends up on a missing page. But I think that the customized 404 page should differ remarkably from the original site layout so that there’s no doubt about you’ve ended up on a “missing” page. I’ve seen 404 pages that are impossible to tell apart from the site and it can take quite some time before you realize you’ve reached a dead end.
I’ve used a customized 404 page on our sites at work almost since day one. The feedback to the visitor can be better but I have an email function – like suggested in the article at A List Apart – that sends an email to me, telling which URL the visitor tried to access and which URL the visitor came from, when someone reaches a missing page from a link, internal or external.
And I must say that this function is really, really helpful. If the broken link is on another site I usually send them an email notifying them about the problem and giving them the correct link – sometimes you just need to re-structure your site, even though it should be avoided when possible – and mostly they appreciate it and alter their link immediately. Also, when re-structuring, it’s easy to miss a few of your own internal links and with the little email notification the problem can be fixed right away.
In Roxen (the CMS we use at work) terms, all that needs to be done is adding this little snippet to the 404 page template in the administration site, under the “settings” tab for the site in question.