Search Engine Optimisation for a 404

Why optimise a 404 page? Why not? It's another string to your seo bow and it's a legitimate way to bolster your internal linking strategy. You can create another page of potential worth to your site's visitors and of definite worth to your site. It has all the keyword-rich links to the other pages that those pages have themselves (important SEO point!). It takes just two minutes to make from a basic SEO template, and it helps promote your site in a laudable manner!

One thing to be careful of; different ISP's with differing server configurations will serve a 404 page in different ways. Once you've made your 404 and included your search engine optimisation keywords, best ask your ISP themselves how best to implement it.