trello_card_numbers.js

// ==UserScript==
// @name         Trello Card Numbers
// @namespace    http://
// @version      0.1
// @description  Shows card numbers on trello. New cards don't get this usually so you may need to refresh the page.
// @author       Tyler Lemburg
// @match        https://trello.com/*
// @grant        none
// ==/UserScript==

$(document).ready(function () {
    setInterval(function() {
        $('.card-short-id').removeClass('hide').css('margin-right', '4px');
    }, 1000);
});