During February 2011 Google rolled out new top navigation bar, which is used for switching services, access to settings and also account switching. Unlike the old bar, the new one requires 3 clicks to switch account. This simple script currently just adds a few styles to show the available accounts on first click. As of June 2012, this script is…

googlenavbaracctsw.user.js

// ==UserScript==
// @name            Google Navbar Easier Account Switch
// @author          Jan Vlnas
// @namespace       http://jan.vlnas.cz/
// @description     Saves you one click when switching accounts with the new Google top navigation bar.
// @license         Creative Commons Attribution 3.0 Unported License
// @version	        0.0.2
// @include        http://*.google.tld/*
// @include        https://*.google.tld/*
// @include        http://google.tld/*
// @include        https://google.tld/*
// @exclude        http*://mail.google.tld/*ui=1*
// ==/UserScript==

/* Include domains ripped from
 * Google Account Multi-Login by Jarrett
 * http://userscripts.org/scripts/show/16341
 */

if (typeof GM_addStyle == "undefined")
{
	function GM_addStyle(css)
	{
		var heads = document.getElementsByTagName("head");
		if (heads.length > 0)
		{
			var node = document.createElement("style");
			node.type = "text/css";
			node.appendChild(document.createTextNode(css));
			heads[0].appendChild(node); 
		}
	}
}

var style = '#gbmpal .gbmpal2, #gbmp2, #gbmps .gbmptc, #gbmpsb {display: none;} #gbmps {display: block !important;}';

GM_addStyle(style);