A userscript for TamperMonkey. All urls starting with dev. or ending in .dev will have a changed favicon. Slightly altered version of http://userscripts.org/scripts/show/42247. Icon from: http://www.favicon.cc/?action=icon&file_id=350544

devicon.userscript.js

// ==UserScript==
// @name       Replace favicon for your development sites
// @namespace  http://itinko.nl/
// @version    1.0
// @description  All urls starting with dev. or ending in .dev will have a changed favicon. Slightly altered version of http://userscripts.org/scripts/show/42247. Icon from: http://www.favicon.cc/?action=icon&file_id=350544
// @match      http://*.dev/*
// @match      http://dev.*/*
// @copyright  2013+, Björn Kuipers
// ==/UserScript==

(function(d, h) {
  // Create this favicon
	var ss = d.createElement('link');
	ss.rel = 'shortcut icon';
	ss.type = 'image/x-icon';
	ss.href = 'data:image/x-icon;base64,AAABAAEAEBAAAAAAAABoBQAAFgAAACgAAAAQAAAAIAAAAAEACAAAAAAAAAEAAAAAAAAAAAAAAAEAAAAAAAAMDQ0AB9jwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQEBAAAAAAEBAQABAQAAAAABAQAAAAABAQAAAAEAAAAAAQEAAAAAAQEAAAABAAAAAAABAAAAAAEAAAAAAAAAAQAAAQAAAQEBAAABAAAAAAEAAAEAAAEBAQAAAQAAAAABAAABAAAAAAEAAAEAAAAAAQAAAQAAAAABAAABAAAAAAEAAAEAAAAAAQAAAQAAAAABAAABAAAAAAEAAAEAAAAAAQAAAQAAAQEBAAABAAAAAAEAAAEAAAEBAQAAAQAAAAAAAAABAAAAAAEAAAEAAAAAAAABAQAAAAABAAABAAAAAAAAAQEAAAAAAQAAAQAAAAAAAQEBAAAAAAEAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=';
	// Remove any existing favicons
	var links = h.getElementsByTagName('link');
	for (var i=0; i<links.length; i++) {
		if (links[i].href == ss.href) return;
		if (links[i].rel == "shortcut icon" || links[i].rel=="icon")
			h.removeChild(links[i]);
	}
	// Add this favicon to the head
	h.appendChild(ss);
	// Force browser to acknowledge
	var shim = document.createElement('iframe');
	shim.width = shim.height = 0;
	document.body.appendChild(shim);
	shim.src = "icon";
	document.body.removeChild(shim);

})(document, document.getElementsByTagName('head')[0]);