No, they're not my products. They're products from large companies. The difference between my site and most every other site in my niche is that I get high-res image files from the manufacturers whenever possible, and Photoshop them to make them look as good as possible.
So, I have a lot of good-looking large images of products that people want to link to from forums, blogs, etc.
Most people link to the page, but many hotlink the photo.
There's far too many photos now to go through and change the file names and links to all of them. Blocking hotlinking would have to be done with a rewrite of some sort.