I just downloaded and have been playing with a firefox extension called Greasemonkey. Holy crap this thing is cool. It essentially allows people to write scripts that can reformat webpages on the fly as they are presented to you. For example; go look at yahoo.com just take a look at all those ads. Now install the no ad script for greasemonkey and refresh the page. Voila! No more ads. There are literally hundreds of scripts that do all manner of things, ad removal just happens to be the most helpful. I know, I know, many of these sites rely on ad revenue. But I honesty don't feel very guilty about it. The scripts can also be uninstalled if you want your webpages the way they were.
I'm not sure how the extension works. If it intercepts the html on its way to the browser it might save valuable time for dial up connections. Go check it out for yourself.
UPDATE: It looks like the content downloads as normal, then is reformated by the script. No bandwidth savings here, but still very cool.