Redirects google searches starting with bang to duckduckgo.com. This way you can keep google (or whatever) as your default search engine so that when you 'cat' in the address bar, google is searched. But, when you type '!yt cat', youtube is searched, bec

google-duckduckgo.user.js

// ==UserScript==
// @name          Google + DuckDuckGo
// @namespace     http://jeffpalm.com/googleduckduckgo/
// @description   Redirects google searches starting with bang to duckduckgo.com
// @include       https://www.google.com/*
// @include       http://www.google.com/*
// ==/UserScript==

(function() {

    function cgiParams(url) {
	var path = url.replace(/.*\?/,'');
	var pairs = path.split(/&/);
	var res = {};
	for (var i=0; i<pairs.length; i++) {
	    var p = pairs[i].split(/=/);
	    var k,v;
	    if (p.length == 2) {
		k = p[0];
		v = p[1];
	    } else {
		k = p[0];
		v = "";
	    }
	    res[k] = v;
	}
	return res;
    }
    
    function main() {
	var url = String(document.location);
	var params = cgiParams(url);
	var q = params['q'];
	if (!!q) {
	    if (q.match(/^!/)) {
		document.location = 'https://duckduckgo.com/?q=' + q;
	    }
	}
    }
    
    main();
    
})();