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Forum Moderators: phranque
Build a site map on your 404; not too cluttered, and with "what's new" and "hot topics" links.
Just don't make it look like a portal, or the visitor may feel redirected.
And of course, a big link to the homepage at the top and the bottom.
<meta http-equiv="Pragma" content="no-cache">
<meta name="robots" content="FOLLOW,NOINDEX">