A way to make resizable fonts accessible.

accessible-resizable-fonts.css

.fontSize80 { font-size: 80% !important; }
.fontSize90 { font-size: 90% !important; }
.fontSize100 { font-size: 100% !important; }
.fontSize110 { font-size: 110% !important; }
.fontSize120 { font-size: 120% !important; }
.fontSize130 { font-size: 130% !important; }
.fontSize140 { font-size: 140% !important; }
.fontSize150 { font-size: 150% !important; }
.fontSize160 { font-size: 160% !important; }
.fontSize170 { font-size: 170% !important; }
.fontSize180 { font-size: 180% !important; }
.fontSize190 { font-size: 190% !important; }
.fontSize200 { font-size: 200% !important; }

accessible-resizable-fonts.html

<ul>
	<li><a href="#" class="increaseFontSize" title="Increase font size">Increase font size</a></li>
	<li><a href="#" class="normalFontSize" title="Normal font size">Normal font size</a></li>
	<li><a href="#" class="decreaseFontSize" title="Decrease font size">Decrease font size</a></li>
</ul>

accessible-resizable-fonts.js

// Read cookie
function getCookie(strCookie){
	var strName = strCookie + "=";
	var arrCookies = document.cookie.split(';');
	for (var i = 0; i < arrCookies.length; i++) {
		var strValorCookie = arrCookies[i];
		while (strValorCookie.charAt(0) == ' ') {
			strValorCookie = strValorCookie.substring(1, strValorCookie.length);
		}
		if (strValorCookie.indexOf(strName) == 0) {
			return strValorCookie.substring(strName.length, strValorCookie.length);
		}
	}
	return '';
}

// Set cookie
function setCookie(name, value, expires, path, domain, secure) {
	// set time, it's in milliseconds
	var today = new Date();
	today.setTime( today.getTime() );

	/*
	if the expires variable is set, make the correct
	expires time, the current script below will set
	it for x number of days, to make it for hours,
	delete * 24, for minutes, delete * 60 * 24
	*/
	path = '/';
	if ( expires ) {
		expires = expires * 1000 * 60 * 60 * 24;
	}
	var expires_date = new Date( today.getTime() + (expires) );
	document.cookie = name + "=" +escape( value ) +
	( ( expires ) ? ";expires=" + expires_date.toGMTString() : "" ) +
	( ( path ) ? ";path=" + path : "" ) +
	( ( domain ) ? ";domain=" + domain : "" ) +
	( ( secure ) ? ";secure" : "" );
}

// Resize font
function resizeFont(signal){
	var size = 100;
	var cookieSize = getCookie ("fontSize");
	if (cookieSize != ""){
		setFontSize(cookieSize);
		size = parseInt(cookieSize);
	}
	if (signal == "plus" && size < 200) {
		size += 10;
	} else if (signal == "minus" && size > 80) {
		size -= 10;
	} else if (signal == "normal") {
		size = 100;
	}
	setFontSize(size);
}

// Set Font Size
function setFontSize(fontSize){
	var cookieSize = getCookie("fontSize");
	// Set the containers that will have their fonts resized
	var ids_containers = ['top','menu','content','footer'];
	for (i=0; i<ids_containers.length; i++) {
		var container = document.getElementById(ids_containers[i]);
		if (container) {
			$("#" + container.id).removeClass("fontSize" + cookieSize);
			$("#" + container.id).addClass("fontSize" + fontSize);
		}
	}
	if (cookieSize != fontSize){
		setCookie("fontSize", fontSize);
	}
}

$(document).ready(function() {
	var cookieSize = getCookie("fontSize");
	if (cookieSize != ""){
		setFontSize(cookieSize);
	}
	$("a.increaseFontSize").click(function(){
		resizeFont("plus");
		return(false);
	}); 
	$("a.decreaseFontSize").click(function(){
		resizeFont("minus");
		return(false);
	});
	$("a.normalFontSize").click(function(){
		resizeFont("normal");
		return(false);
	});
});