4gamerViewer.user.js

// ==UserScript==
// @name           4gamerViewer
// @namespace      http://d.hatena.ne.jp/arikui/
// @description    http://userscripts.org/scripts/show/39290
// @include        http://www.4gamer.net/
// @require        http://gist.github.com/raw/3242/9dc0cdee5e975d275c7ab71f581d272eb316674f
// ==/UserScript==
(function(){
	var thumbnail = document.createElement("div");
	var newsDay1  = document.getElementById("NEWS_SELECT_DAY_1");

	Array.slice.call([], document.getElementsByClassName("img_right_top")).forEach(function(image){
		thumbnail.appendChild(image.parentNode.cloneNode(true));
	});

	thumbnail.style.display = "none";
	newsDay1.parentNode.insertBefore(thumbnail, newsDay1);

	$X("//div[@class='finding_common']/ul")[0].appendChild((function(){
		var li    = document.createElement("li");
		var label = document.createElement("label");
		var input = document.createElement("input");

		input.type = "checkbox";

		li.appendChild(label);
		label.appendChild(input);
		label.appendChild(document.createTextNode("Thumbnail"));

		input.addEventListener("click", function(){
			thumbnail.style.display = this.checked ? "block" : "none";
		}, false);

		return li;
	})());
})();