Add support for bold and emphasized Markdown in Trello card titles using a User Script.

trello-card-title-markdown.user.js

// ==UserScript==
// @name Trello card title Markdown
// @version 0.4.0
// @homepage https://gist.github.com/gorbiz/6062481
// @description Add support for bold and emphasized Markdown in card titles
// @match https://trello.com/b/*
// @match http://trello.com/b/*
// ==/UserScript==

/***
 * "Bold and emphasized Markdown in Trello card titles",
 * am awesome mini Chrome Extension forked from @gorbiz :-)
 *
 * Supports bolding, emphasizing & code styling.
 *
 * Install in Chrome or Chromium
 * 1. Download the script.
 * 2. Open chrome://extensions/ in the browser.
 * 3. Drag the downloaded file to the browser window.
 *
 */

function markdownAll() {
	var cards = document.getElementsByClassName('list-card-title');
	for (var i = 0; i < cards.length; i++) {
		cards[i].innerHTML = cards[i].innerHTML
		    .replace(/\*\*(.+?)\*\*/g, '<strong>$1</strong>')
		    .replace(/\*(.+?)\*/g, '<em>$1</em>')
		    .replace(/~~(.+?)~~/g, '<strike>$1</strike>')
		    .replace(/\`(.+?)\`/g, '<code>$1</code>');
	}
	setTimeout(markdownAll, 500);
}

markdownAll();

Install in Chrome or Chromium

1. Download the script.
2. Open chrome://extensions/ in the browser.
3. Drag the downloaded file to the browser window.

Original code: https://gist.github.com/gorbiz/6062481

Awesome - exactly what I was looking for!!
Hahah... was about to thank you for this great extension & perhaps mention that I once made something similar... 😆