This is
nop again. OK, this is really simple and crude, but this small javascript hack does slow down the basic click-and-save image grabbers. Yes, they can view source and get the image URL there, but that's more inconvenient, plus (as our pages are graphics-rich with images, banners, logos, nav elements, etc) it takes a few moments to find the right IMG tag in the source. Here's a site using it:
http://www.marvelcreations.com/priv15.html
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Right click on their images and try to save them.