Mark visited links with a significant color, to see in your dashboard which repos you already visited.

github-visited-links-userscript.js

// ==UserScript==
// @name       Mark Visited Links on GitHub
// @namespace  http://github.visited.links/
// @version    0.1
// @description Mark visited links with a significant color, to see in the repos you have already visited.
// @match      https://github.com/
// @copyright  2014, Pascal Weiland
// ==/UserScript==

(function() {
    
    var css = document.createElement("style");
	css.type = "text/css";
    css.innerHTML = "#dashboard a:visited { color: #cc0000 }";
	document.body.appendChild(css);
    console.log('Added css');
})();