Actually i lied... i did have the code in my bookmarks hehe.

RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://domain.com.*$ [NC]
RewriteCond %{HTTP_REFERER} !^http://www.domain.com.*$ [NC]
RewriteCond %{HTTP_REFERER} !^http://domain.com:80.*$ [NC]
RewriteCond %{HTTP_REFERER} !^http://www.domain.com:80.*$ [NC]
RewriteCond %{HTTP_REFERER} !^http://i.p.ad.dre.ss*$ [NC]
RewriteCond %{HTTP_REFERER} !^http://i.p.ad.dre.ss:80.*$ [NC]
RewriteRule .*[Jj][Pp][Gg]$|.*[Gg][Ii][Ff]$ http://www.domain.com/imagename.jpg
In the above code, imagename.jpg would be the location of an image on your server that literally has either the url to one of your sites on it or, some message along the lines of the site that the surfer is seeing that image on is being run by a theif.. either way your call personally i would go the URL route myself

Hope that helps.

Regards,

Lee