I just realize that there is huge bandwidth leak at my site. I see it at my cpanel bandwidth meter. Wew, one of my picture at my blog linked by big bookmarking site. That would waste many bandwidth. After that, I immediately activate my hot link protection at cpanel.
How to setting it up?
1. Click link Hotlink protection menu
2. Fill URLs to allow access section with URL able to link at your picture
3. Fill the image extension that not allowed to link in Block direct access for these extensions (separate by commas) section
note: http://www.yoursite.com is different with yoursite.com, so fill your domain in step 2 with www and without www.
To disable hotlink with htaccess you can see it here