The Google Maps model gave us our first high-profile insight into what can happen on a website when it doesn't wait for the user to do something to prepare what might next need displaying. By downloading the maps immediately surrounding the map you're looking at, it allowed you to drag around the map seamlessly. It was revolutionary and was the forerunner for that horrible phrased, Web 2.0.
Most webpages, this one included at the time of writing, don't do that. They display a page complete with a bunch of links to unloaded pages and wait for the user to click one before doing anything. What if there was a little link counter running in the background that weighted each link on a page based on its likelihood of being clicked according to users' behaviour? And then some Firefox plug-in came along and on accessing a page, called the associated weighting information and started downloading the pages in the background in descending order of weight. Then if the user happened to click one of the most popular links, the page would appear instantly. Maybe the idea is superseded by the speed offered by broadband, but I'd like to think not.



