bootswatchlet.js

javascript: (function (w) {
    if (!w.jQuery) {
        alert('jQuery is required.');
        return;
    }
    if ($('#bootswatch').length) {
    	alert('Bookmaklet already loaded.');
    	return;
    }
    var $link = $('<link>', {
        rel: 'stylesheet',
        id: 'bootswatch'
    }).appendTo('head');
    var $select = $('<select>', {
        css: {
            top: 8,
            right: 8,
            position: 'fixed',
            zIndex: 999999
        },
        html: '<option value="null">Bootswatch</option>'
    }).appendTo('body');
    $select.on('change', function (e) {
        var value = $select.val();
        value && $link.attr('href', value);
    });
    $.ajax({
        url: 'http://api.bootswatch.com/3/'
    }).done(function (data, status, xhr) {
        data.themes.forEach(function (val, key) {
            $select.append('<option value="' + val.cssCdn + '">' + val.name + '</option>');
        });
    });
})(window);

better version it autoload jquery
javascript:(function(){var e=document.createElement("script");e.src="//code.jquery.com/jquery-latest.min.js";e.setAttribute("async","true");document.documentElement.firstChild.appendChild(e)})();(function(e){if(!e.jQuery){alert("jQuery is required.");return}if($("#prit-bootswatch").length){alert("Bookmaklet already loaded.");return}var t=$("",{rel:"stylesheet",id:"prit-bootswatch"}).appendTo("head");var n=$("",{css:{top:8,right:8,position:"fixed",zIndex:999999},html:'Bootswatch'}).appendTo("body");n.on("change",function(e){var r=n.val();r&&t.attr("href",r)});$.ajax({url:"//api.bootswatch.com/3/"}).done(function(e,t,r){e.themes.forEach(function(e,t){n.append(''+e.name+"")})})})(window);