If your running apache server, you can do what you need by configuring your .htaccess file.

You would do something like this to prevent hotlinking of images –

RewriteEngine on
RewriteCond %{HTTP_REFERER}!^$
RewriteCond %{HTTP_REFERER}!^http://(www\.)?mydomain.com/.*$ [NC]
RewriteRule \.(gif¦jpg¦js¦css)$ – [F]

replace mydomain.com with your domain name and only your domain will be allowed to access files appeneded by .gif .jpg .js or .css

you can add other allowed domaine with extra lines e.g. –

RewriteEngine on
RewriteCond %{HTTP_REFERER}!^$
RewriteCond %{HTTP_REFERER}!^http://(www\.)?mydomain.com/.*$ [NC]
RewriteCond %{HTTP_REFERER}!^http://(www\.)?domain1.com/.*$ [NC]
RewriteCond %{HTTP_REFERER}!^http://(www\.)?domain2.com/.*$ [NC]
RewriteCond %{HTTP_REFERER}!^http://(www\.)?domain3.com/.*$ [NC]
RewriteRule \.(gif¦jpg¦js¦css)$ – [F]