In an earlier post, I had suggested that Google place a search bar in their 404 page.
CNN.com has taken the exact opposite approach of having too many search bars in a 404 page:
They have not one, not two, but three [!!] search bars in their 404 page. Granted two of them are from the header and footer, but still, there’s got to be a better design. I’m sure Google is loving the heavy emphasis on “powered by Google” x 3 on this page.