Google "block hotlinking" for a few tutorials on the .htaccess way. Or if you have CPanel domain management like me, there's a hotlinking blocking tool. But I still have to figure out how to allow hotlinking from wildcarded subdomains - ideally I'd allow any livejournal.com links, but for now I just unprotected the moodtheme and allowed linking from bwinter.livejournal.com and community.livejournal.com. I need to log a support request with the CPanel people :/