Here’s a handy little web-whittle. It lets you save large versions of images from fleeting eBay sales listings, in which images are usually blocked by a javascript lightbox. You don’t need an add-on to save them to your PC.

In Firefox, just go: View | Page Style | No Style. This strips all formatting off the page.

Then scroll down to the bottom of what is now a much longer page than before, and near the bottom you’ll see the 1600px size pictures. You can the right-click on the picture and save.