This is probably not very important for most people, but when I was designing my custom preloader I found it quite difficult to get it looking exactly right - the positioning, font sizes, image location, etc. And so I was constantly reloading to see the preloader appear again.
So I wrote this simple test to show the preloader again after the application has loaded. This way you can control how long the preloader is visible for, and you don't have to add all these large images to make it slow to load.
** Here is the link to my previous blog post on Custom preloaders. It also contains some useful links to other websites and tutorials on custom preloaders.
Right Click to View Source: