(I don't want to disable hotlinking completely.)
You can block individual sites by using this:
RewriteCond %{HTTP_REFERER} ^
http://(.+\.)?site\.com/ [NC]
such as:
RewriteCond %{HTTP_REFERER} ^
http://(.+\.)?fusker\.lv/ [NC]
but what if I want to block every site that has the text "fusker" anywhere in the url? How do I do that?