I recently found a Firefox Addon that I really like called Stylish. It's a bit like Greasemonkey but rather than modifing the Java, it lets you mess around with the CSS. I've downloaded a bunch of scripts from http://userstyles.org for all the sites I visit a lot and even made one of my own for the forums (it's nowhere near done but the actual topic pages are more than readable).
You can check out the addon here: [link]
