Inject jQuery and lodash into the current tab via a bookmarklet. To use, just create a new bookmark and use this as the URL.

gistfile1.js

javascript: (function () {
  var el = document.createElement('pre'),
    b = document.getElementsByTagName('body')[0],
    otherjQuery = false,
    msg = '',
    libs = [
      function loadjQuery() {
        if (typeof jQuery != 'undefined') {
          showMsg('This page already using jQuery v' + jQuery.fn.jquery);
        } else {
          if (typeof $ == 'function') {
            otherjQuery = true;
          }
          getScript('//cdnjs.cloudflare.com/ajax/libs/jquery/2.0.3/jquery.js', function () {
            if (typeof jQuery == 'undefined') {
              showMsg('Sorry, but jQuery wasn\'t able to load')
            } else {
              showMsg('This page is now jQuerified with v' + jQuery.fn.jquery + otherjQuery ? ' and noConflict(). Use $jq(), not $().' : '');
            }
          });
        }
      },
      function loadLodash() {
        if (typeof _ != 'undefined') {
          showMsg('This page already using lodash v' + _.VERSION);
        }
        getScript('//cdnjs.cloudflare.com/ajax/libs/lodash.js/1.3.1/lodash.min.js', function () {
          showMsg('This page is now has lodash');
        });
      }
    ];
  el.style.position = 'fixed';
  el.style.top = '0';
  el.style.padding = '5px 10px';
  el.style.zIndex = 9001;
  el.style.fontSize = '12px';
  el.style.color = '#222';
  el.style.backgroundColor = '#f99';

  function getScript(url, success) {
    var script = document.createElement('script');
    script.src = url;
    var head = document.getElementsByTagName('head')[0],
      done = false;
    script.onload = script.onreadystatechange = function () {
      if (!done && (!this.readyState || this.readyState == 'loaded' || this.readyState == 'complete')) {
        done = true;
        success();
        script.onload = script.onreadystatechange = null;
        head.removeChild(script);
      }
    };
    head.appendChild(script);
  }

  function showMsg(msg) {
    if (!document.body.contains(el)) {
      b.appendChild(el);
    }
    el.appendChild(document.createTextNode(msg + '\n'));
    window.setTimeout(function () {
      if (typeof jQuery == 'undefined') {
        b.removeChild(el);
      } else {
        jQuery(el).fadeOut('slow', function () {
          jQuery(this).remove();
        });
        if (otherjQuery) {
          $jq = jQuery.noConflict();
        }
      }
    }, 2500);
  }
  libs.forEach(function (init) {
    init();
  })
})();