// ==UserScript==
// @namespace http://nathanpowell.org
// @name I hate everyones fonts!
// @description use my fonts!
// @include *
// @exclude http://localhost*
// ==/UserScript==

var newCss = 'body {' +
			 'font-family: verdana, arial, helvetica, sans-serif;' +
			 '}';

function overRideCSS( newCss ) {
var head = document.getElementsByTagName("head")[0];
var styleTag = document.createElement("style");
styleTag.setAttribute("type", 'text/css');
styleTag.innerHTML = newCss;
head.appendChild(styleTag);
}

overRideCSS( newCss );