Firefox only (Windows/Linux/Mac) : Easily view images in a directory tree—without actually clicking through to every image—with Firefox extension Unlinker. The extension embeds itself into your right-click menu and offers many options for an improved web surfing experience. My favorite: the Convert in Page option, which turns the directory tree into a page filled with pictures so that you can browse the items in the directory tree before you actually download them. Unlinker features other options, including the ability to view graphics in a new window, to download all of the images locally, and to save all images to the clipboard. Unlinker is free, works whenever Firefox does.
Source : LifeHacker