This is just the coolest thing. I was looking for a script that would preload images and show a status bar based on the progress, and this is what I found. Very easy to use/setup!
(Little side note/disclaimer: If you use this kind of thing on a regular webpage – your users may get annoyed that they have to wait while the images load before they can go to your site. So, this may or may not be useful for the 'general public.' In my case, this suited a very particular need perfectly.)