Cover your hosted Images with a transparent GIF to hinder image theft
A TransGif is a transparent gif (empty) image, with your own image set as the background.
Normal right-click copy techniques will pick up the empty image and leave the background behind.
This method provides a little bit of security for hosted images where you have control over the code
to display those images.
A negative aspect of using a TransGif is that it may not appear on printouts unless the user has enabled background printing.
TransGifs only work for normal pictures and icons, and can't be used for page or border background images, or for images that are inserted in a page beyond your control (like eBay Picture Services).