A tweet-sized JavaScript Image Preloader.
To use:
var preload = function(a,b){a=[].slice.call(arguments),b=a.length;for(;b--;){Image().src=a[b]}};
preload('http://www.google.com/images/logos/ps_logo2.png', 'http://localhost:8080/images/myimage.png', 'image1.jpg');