It began with AdBlock... this extension to Firefox automatically removes adverts from the pages you browse - including the most annoying animated Flash horrors. It even updates itself to make sure that it stays one step ahead of ad-serving sites.
Unfortunately there were a couple of persistant sites that remained troublesome to visit. One of those was Football365, which used Javascript to include a couple of diversions, including a speedy tickertape (and we all know how annoying those can be). In stepped NoScript, which allows you to set up a whitelist of sites which should be allowed to run scripts. Bye bye ticker tape!
So now I had a calm and much less cluttered Football365. I remember a Firefox feature which would let me take it a step further. A custom UserContent.css allows you to write a CSS targetted to specific domains, meaning you can completely override the styling of a given website. For F365 I removed a couple of blocks I wasn't interested in or that cluttered things up, made the layout full width, and increased the font size a little, as well as a few other little tidying tweaks.
From an fixed-width animated monster with sound-effect ridden adverts, I've now got a sane and readable site which doesn't torment me with its layout, and in just three simple steps. The most dramatic of these is possible due to the use of a CSS layout underlying the F365 pages, a handy piece of foresight by their web team.