We did something like this at Yahoo! with an R&D project that never saw the light of day. The functionality was later integrated with Yahoo! toolbar. I think

We did something like this at Yahoo! with an R&D project that never saw the light of day. The functionality was later integrated with Yahoo! toolbar. I think it was called 'Speedboost' or something like that. I'm not a fan of browser toolbars and it was around the time that I left so I don't remember much about how it was being marketed. It took all the visual aspects of Yahoo! properties and 'pushed' them to the IE and FF cache so that when a user visited any number of Yahoo! properties, most of the visuals had already been loaded in the background.