One good use for document.load is to pre-load your images, then you know that they will work for your mouseovers and animations. All that stuff has to already "be there" at the user's browser - in order for them to see it. Code to cache an image:

var myImage = new Image();
var myImage.src = "ship.gif"

As usual, setting up a variable to hold the information allows javascript to remember this picture.

So, we declare the variable and set it equal to a new imaage., tell javascript where to find the picture and now, the picture is loaded.

The document has an onLoad() event, that in this case I included in the <body> tag (check the source)
Using this function, I am able to tell the browser to go execute that function.

So of course, I wanted to use this time to start pre-loading (or cache) my images.