Name: Trackback Spam
Version: 1.1
Description: Denies obvious trackback spam.  See <a href="http://ocaoimh.ie/2008/07/03/more-ways-to-stop-spammers-and-unwanted-traffic/">Holy Shmoly!</a>
Rules: 
RewriteCond %{HTTP_USER_AGENT} ^.*(opera|mozilla|firefox|msie|safari).*$ [NC,OR]
RewriteCond %{HTTP_USER_AGENT} ^-?$
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.+/trackback/?\ HTTP/ [NC]
RewriteCond %{REQUEST_METHOD} =POST
RewriteRule .* - [F,NS,L]