sem4u - 1:57 pm on Nov 17, 2011 (gmt 0)
I usually block hotlinking of images as I used to have big problems with people linking to my images from myspace profiles, etc. It would just suck up the bandwidth.
I am sure that there is some SE value from having people hotlink your images, but you have to weigh it up with the possible bandwidth costs.
You could also have some fun with hotlinkers by renaming an image on your site. Keep the old one up, but change it to something like "this site is stealing an image from example.com". You soon find that people stop hotlinking ;)