Userscript that enables sensible defaults for jsFiddle.

jsfiddle-defaults.user.js

// ==UserScript==
// @name Sensible defaults for jsFiddle.
// @author Mathias Bynens <http://mathiasbynens.be/>
// @link http://mths.be/bde
// @match http://jsfiddle.net/*
// ==/UserScript==

// Ignore existing fiddles
if (window.location.pathname == '/') {

	// Insert JS before </body> and don’t use any libraries by default
	[].forEach.call(document.querySelectorAll('#js_wrap option[value="b"], #js_lib option[value="11"]'), function(el) {
		el.selected = true;
	});

	// Don’t use the “normalized” CSS (it’s more like a reset anyway)
	document.getElementById('id_normalize_css').checked = false;

}

We'll change the wording the the future versions of JsFiddle, so there's no confusion

Thanks Oskar, that’d be great!

Is this used in greasemonkey or can it somehow be added in gist? Seems like the former?
Which means its no good for sharing jsfiddle/gists unless I get recipients to install GM and this userscript :/ Which means we really need jsfiddle to fix this - https://github.com/jsfiddle/jsfiddle-docs-alpha/issues/44. Thanks.

I was asked how to disable the sidebar by default. You could add this to the userscript:

document.getElementById('sidebar').style.cssText = 'display: none; min-height: 525px;';
document.getElementById('content').style.marginLeft = '13px';

…or just use unsafeWindow.Layout.sidebar.hide(); (probably combined with the unsafeWindow polyfill).