404 traffic - making something out of nothing: we are looking for pay-per-click search engines and directories that will pay us for our 404 traffic.
Searchfeed has a 404 page they offer. If you sign up through my link ( http://www.searchfeed.com/rd/AffiliateInfo.jsp?p=22415 ) and tell them you signed up as a portxml client, they are supposed to give you an extra 5%.
404 traffic is traffic to non existant pages on your site, it could be typos, pages that got moved ( uncool you!! http://www.w3.org/Provider/Style/URI ), or traffic from an old site if the domain was in use before.