Going back up slowly..
Now with thumbnails AND Slideshows for your browsing enjoyment!
ps. I recommend Firefox or Chrome for desktop web browsing. NOTE: The thumbnailer will re-use the big image window. If you allow pop-ups, it automatically pops to the front and resizes to fit the image (unless you are fullscreen, in which case it leaves the size alone). If you have the windoid fullscreen, it's easy to Alt+Tab back to the thumbnails. If you have two monitors, stick your browser on the smaller, the pop-up on the bigger and enjoy!
If you want to grab the whole lot in one go (from the index page), install the "DownThemAll" extension, it makes that sort of thing easy.
If you are on a mobile browser, I recommend you select fullscreen mode (and the QuickSlideshow, if available) for the best experience. Tap either side of the image to go back and forward.
Note: the slideshow downloads the next image in the background - the longer you spend enjoying each image, the more chance the next image will be instantly available! A progress indicator lets you know when it's ready. And yes, you can use your arrow keys.