Searching Duck Duck Go for "show hn" shows that you can search HNsearch with their !bang syntax: http://duckduckgo.com/?q=show+hn
http://www.unscatter.com/search/?q=duckduckgo+%2Fhn http://www.unscatter.com/search/?q=duckduckgo+%2Fhnstories&#... http://www.unscatter.com/search/?q=duckduckgo+%2Fhncomments&...
I didn't win, but I added it as an entry for that contest a while back.